diff --git a/blockdag/dag_test.go b/blockdag/dag_test.go
index 891d95416..8f64a5b4c 100644
--- a/blockdag/dag_test.go
+++ b/blockdag/dag_test.go
@@ -894,7 +894,7 @@ func TestFinality(t *testing.T) {
 		}
 		msgBlock := wire.NewMsgBlock(bh)
 		blockHeight := parents.maxHeight() + 1
-		coinbaseTx, err := createCoinbaseTx(blockHeight, 1, extraNonce, dag.dagParams)
+		coinbaseTx, err := createCoinbaseTxForTest(blockHeight, 1, extraNonce, dag.dagParams)
 		if err != nil {
 			return nil, err
 		}
diff --git a/blockdag/error.go b/blockdag/error.go
index 02d97fa17..0c325a257 100644
--- a/blockdag/error.go
+++ b/blockdag/error.go
@@ -216,6 +216,10 @@ const (
 	// sorted by sub-network
 	ErrTransactionsNotSorted
 
+	// ErrInvalidGas transaction wants to use more GAS than allowed
+	// by subnetwork
+	ErrInvalidGas
+
 	// ErrSubNetwork indicates that a block doesn't adhere to the sub-network
 	// registry rules
 	ErrSubNetworkRegistry
@@ -265,6 +269,7 @@ var errorCodeStrings = map[ErrorCode]string{
 	ErrWithDiff:                  "ErrWithDiff",
 	ErrFinality:                  "ErrFinality",
 	ErrTransactionsNotSorted:     "ErrTransactionsNotSorted",
+	ErrInvalidGas:                "ErrInvalidGas",
 }
 
 // String returns the ErrorCode as a human-readable name.
diff --git a/blockdag/error_test.go b/blockdag/error_test.go
index 0e0efe02a..218a86a96 100644
--- a/blockdag/error_test.go
+++ b/blockdag/error_test.go
@@ -57,6 +57,7 @@ func TestErrorCodeStringer(t *testing.T) {
 		{ErrWithDiff, "ErrWithDiff"},
 		{ErrFinality, "ErrFinality"},
 		{ErrTransactionsNotSorted, "ErrTransactionsNotSorted"},
+		{ErrInvalidGas, "ErrInvalidGas"},
 		{0xffff, "Unknown ErrorCode (65535)"},
 	}
 
diff --git a/blockdag/subnetworks_test.go b/blockdag/subnetworks_test.go
index 5571b9f6a..e5fd370b6 100644
--- a/blockdag/subnetworks_test.go
+++ b/blockdag/subnetworks_test.go
@@ -2,13 +2,12 @@ package blockdag
 
 import (
 	"encoding/binary"
-	"github.com/daglabs/btcd/dagconfig"
-	"github.com/daglabs/btcd/util"
-	"github.com/daglabs/btcd/wire"
 	"math"
 	"reflect"
 	"testing"
-	"time"
+
+	"github.com/daglabs/btcd/dagconfig"
+	"github.com/daglabs/btcd/wire"
 )
 
 // TestSubNetworkRegistry tests the full sub-network registry flow. In this test:
@@ -25,89 +24,11 @@ func TestSubNetworkRegistry(t *testing.T) {
 		t.Fatalf("Failed to setup DAG instance: %v", err)
 	}
 	defer teardownFunc()
-	blockTime := time.Unix(dag.genesis.timestamp, 0)
-	extraNonce := int64(0)
 
-	buildNextBlock := func(parents blockSet, txs []*wire.MsgTx) (*util.Block, error) {
-		// We need to change the blockTime to keep all block hashes unique
-		blockTime = blockTime.Add(time.Second)
+	_, err = RegisterSubnetworkForTest(dag, 12345)
 
-		// We need to change the extraNonce to keep coinbase hashes unique
-		extraNonce++
-
-		bh := &wire.BlockHeader{
-			Version:      1,
-			Bits:         dag.genesis.bits,
-			ParentHashes: parents.hashes(),
-			Timestamp:    blockTime,
-		}
-		msgBlock := wire.NewMsgBlock(bh)
-		blockHeight := parents.maxHeight() + 1
-		coinbaseTx, err := createCoinbaseTx(blockHeight, 1, extraNonce, dag.dagParams)
-		if err != nil {
-			return nil, err
-		}
-		_ = msgBlock.AddTransaction(coinbaseTx)
-
-		for _, tx := range txs {
-			_ = msgBlock.AddTransaction(tx)
-		}
-
-		return util.NewBlock(msgBlock), nil
-	}
-
-	addBlockToDAG := func(block *util.Block) (*blockNode, error) {
-		dag.dagLock.Lock()
-		defer dag.dagLock.Unlock()
-
-		err = dag.maybeAcceptBlock(block, BFNone)
-		if err != nil {
-			return nil, err
-		}
-
-		return dag.index.LookupNode(block.Hash()), nil
-	}
-
-	currentNode := dag.genesis
-
-	// Create a block with a valid sub-network registry transaction
-	gasLimit := uint64(12345)
-	registryTx := wire.NewMsgTx(wire.TxVersion)
-	registryTx.SubNetworkID = wire.SubNetworkRegistry
-	registryTx.Payload = make([]byte, 8)
-	binary.LittleEndian.PutUint64(registryTx.Payload, gasLimit)
-
-	// Add it to the DAG
-	registryBlock, err := buildNextBlock(setFromSlice(currentNode), []*wire.MsgTx{registryTx})
 	if err != nil {
-		t.Fatalf("could not build registry block: %s", err)
-	}
-	currentNode, err = addBlockToDAG(registryBlock)
-	if err != nil {
-		t.Fatalf("could not add registry block to DAG: %s", err)
-	}
-
-	// Add 2*finalityInterval to ensure the registry transaction is finalized
-	for currentNode.blueScore < 2*finalityInterval {
-		nextBlock, err := buildNextBlock(setFromSlice(currentNode), []*wire.MsgTx{})
-		if err != nil {
-			t.Fatalf("could not create block: %s", err)
-		}
-		currentNode, err = addBlockToDAG(nextBlock)
-		if err != nil {
-			t.Fatalf("could not add block to DAG: %s", err)
-		}
-	}
-
-	// Make sure that the sub-network had been successfully registered by trying
-	// to retrieve its gas limit.
-	mostRecentlyRegisteredSubNetworkID := dag.lastSubNetworkID - 1
-	limit, err := dag.GasLimit(mostRecentlyRegisteredSubNetworkID)
-	if err != nil {
-		t.Fatalf("could not retrieve gas limit: %s", err)
-	}
-	if limit != gasLimit {
-		t.Fatalf("unexpected gas limit. want: %d, got: %d", gasLimit, limit)
+		t.Fatalf("could not register network: %s", err)
 	}
 }
 
diff --git a/blockdag/test_utils.go b/blockdag/test_utils.go
index 3fcbe36c7..5cb794a6a 100644
--- a/blockdag/test_utils.go
+++ b/blockdag/test_utils.go
@@ -1,13 +1,18 @@
 package blockdag
 
 import (
+	"encoding/binary"
 	"fmt"
 	"os"
 	"path/filepath"
+	"time"
 
+	"github.com/daglabs/btcd/dagconfig"
+	"github.com/daglabs/btcd/dagconfig/daghash"
 	"github.com/daglabs/btcd/database"
 	_ "github.com/daglabs/btcd/database/ffldb" // blank import ffldb so that its init() function runs before tests
 	"github.com/daglabs/btcd/txscript"
+	"github.com/daglabs/btcd/util"
 	"github.com/daglabs/btcd/wire"
 )
 
@@ -94,3 +99,134 @@ func DAGSetup(dbName string, config Config) (*BlockDAG, func(), error) {
 	}
 	return dag, teardown, nil
 }
+
+// OpTrueScript is script returning TRUE
+var OpTrueScript = []byte{txscript.OpTrue}
+
+// createCoinbaseTxForTest returns a coinbase transaction with the requested number of
+// outputs paying an appropriate subsidy based on the passed block height to the
+// address associated with the harness.  It automatically uses a standard
+// signature script that starts with the block height
+func createCoinbaseTxForTest(blockHeight int32, numOutputs uint32, extraNonce int64, params *dagconfig.Params) (*wire.MsgTx, error) {
+	// Create standard coinbase script.
+	coinbaseScript, err := txscript.NewScriptBuilder().
+		AddInt64(int64(blockHeight)).AddInt64(extraNonce).Script()
+	if err != nil {
+		return nil, err
+	}
+
+	tx := wire.NewMsgTx(wire.TxVersion)
+	tx.AddTxIn(&wire.TxIn{
+		// Coinbase transactions have no inputs, so previous outpoint is
+		// zero hash and max index.
+		PreviousOutPoint: *wire.NewOutPoint(&daghash.Hash{},
+			wire.MaxPrevOutIndex),
+		SignatureScript: coinbaseScript,
+		Sequence:        wire.MaxTxInSequenceNum,
+	})
+	totalInput := CalcBlockSubsidy(blockHeight, params)
+	amountPerOutput := totalInput / uint64(numOutputs)
+	remainder := totalInput - amountPerOutput*uint64(numOutputs)
+	for i := uint32(0); i < numOutputs; i++ {
+		// Ensure the final output accounts for any remainder that might
+		// be left from splitting the input amount.
+		amount := amountPerOutput
+		if i == numOutputs-1 {
+			amount = amountPerOutput + remainder
+		}
+		tx.AddTxOut(&wire.TxOut{
+			PkScript: OpTrueScript,
+			Value:    amount,
+		})
+	}
+
+	return tx, nil
+}
+
+// RegisterSubnetworkForTest is used to register network on DAG with specified GAS limit.
+func RegisterSubnetworkForTest(dag *BlockDAG, gasLimit uint64) (subNetworkID uint64, err error) {
+	blockTime := time.Unix(dag.genesis.timestamp, 0)
+	extraNonce := int64(0)
+
+	buildNextBlock := func(parents blockSet, txs []*wire.MsgTx) (*util.Block, error) {
+		// We need to change the blockTime to keep all block hashes unique
+		blockTime = blockTime.Add(time.Second)
+
+		// We need to change the extraNonce to keep coinbase hashes unique
+		extraNonce++
+
+		bh := &wire.BlockHeader{
+			Version:      1,
+			Bits:         dag.genesis.bits,
+			ParentHashes: parents.hashes(),
+			Timestamp:    blockTime,
+		}
+		msgBlock := wire.NewMsgBlock(bh)
+		blockHeight := parents.maxHeight() + 1
+		coinbaseTx, err := createCoinbaseTxForTest(blockHeight, 1, extraNonce, dag.dagParams)
+		if err != nil {
+			return nil, err
+		}
+		_ = msgBlock.AddTransaction(coinbaseTx)
+
+		for _, tx := range txs {
+			_ = msgBlock.AddTransaction(tx)
+		}
+
+		return util.NewBlock(msgBlock), nil
+	}
+
+	addBlockToDAG := func(block *util.Block) (*blockNode, error) {
+		dag.dagLock.Lock()
+		defer dag.dagLock.Unlock()
+
+		err = dag.maybeAcceptBlock(block, BFNone)
+		if err != nil {
+			return nil, err
+		}
+
+		return dag.index.LookupNode(block.Hash()), nil
+	}
+
+	currentNode := dag.genesis
+
+	// Create a block with a valid sub-network registry transaction
+	registryTx := wire.NewMsgTx(wire.TxVersion)
+	registryTx.SubNetworkID = wire.SubNetworkRegistry
+	registryTx.Payload = make([]byte, 8)
+	binary.LittleEndian.PutUint64(registryTx.Payload, gasLimit)
+
+	// Add it to the DAG
+	registryBlock, err := buildNextBlock(setFromSlice(currentNode), []*wire.MsgTx{registryTx})
+	if err != nil {
+		return 0, fmt.Errorf("could not build registry block: %s", err)
+	}
+	currentNode, err = addBlockToDAG(registryBlock)
+	if err != nil {
+		return 0, fmt.Errorf("could not add registry block to DAG: %s", err)
+	}
+
+	// Add 2*finalityInterval to ensure the registry transaction is finalized
+	for currentNode.blueScore < 2*finalityInterval {
+		nextBlock, err := buildNextBlock(setFromSlice(currentNode), []*wire.MsgTx{})
+		if err != nil {
+			return 0, fmt.Errorf("could not create block: %s", err)
+		}
+		currentNode, err = addBlockToDAG(nextBlock)
+		if err != nil {
+			return 0, fmt.Errorf("could not add block to DAG: %s", err)
+		}
+	}
+
+	// Make sure that the sub-network had been successfully registered by trying
+	// to retrieve its gas limit.
+	mostRecentlyRegisteredSubNetworkID := dag.lastSubNetworkID - 1
+	limit, err := dag.GasLimit(mostRecentlyRegisteredSubNetworkID)
+	if err != nil {
+		return 0, fmt.Errorf("could not retrieve gas limit: %s", err)
+	}
+	if limit != gasLimit {
+		return 0, fmt.Errorf("unexpected gas limit. want: %d, got: %d", gasLimit, limit)
+	}
+	return mostRecentlyRegisteredSubNetworkID, nil
+}
diff --git a/blockdag/utxoset_test.go b/blockdag/utxoset_test.go
index 098876701..f465c48d6 100644
--- a/blockdag/utxoset_test.go
+++ b/blockdag/utxoset_test.go
@@ -7,13 +7,10 @@ import (
 
 	"github.com/daglabs/btcd/dagconfig"
 	"github.com/daglabs/btcd/dagconfig/daghash"
-	"github.com/daglabs/btcd/txscript"
 	"github.com/daglabs/btcd/util"
 	"github.com/daglabs/btcd/wire"
 )
 
-var OpTrueScript = []byte{txscript.OpTrue}
-
 // TestUTXOCollection makes sure that utxoCollection cloning and string representations work as expected.
 func TestUTXOCollection(t *testing.T) {
 	hash0, _ := daghash.NewHashFromStr("0000000000000000000000000000000000000000000000000000000000000000")
@@ -799,46 +796,6 @@ func TestDiffUTXOSet_addTx(t *testing.T) {
 	}
 }
 
-// createCoinbaseTx returns a coinbase transaction with the requested number of
-// outputs paying an appropriate subsidy based on the passed block height to the
-// address associated with the harness.  It automatically uses a standard
-// signature script that starts with the block height
-func createCoinbaseTx(blockHeight int32, numOutputs uint32, extraNonce int64, params *dagconfig.Params) (*wire.MsgTx, error) {
-	// Create standard coinbase script.
-	coinbaseScript, err := txscript.NewScriptBuilder().
-		AddInt64(int64(blockHeight)).AddInt64(extraNonce).Script()
-	if err != nil {
-		return nil, err
-	}
-
-	tx := wire.NewMsgTx(wire.TxVersion)
-	tx.AddTxIn(&wire.TxIn{
-		// Coinbase transactions have no inputs, so previous outpoint is
-		// zero hash and max index.
-		PreviousOutPoint: *wire.NewOutPoint(&daghash.Hash{},
-			wire.MaxPrevOutIndex),
-		SignatureScript: coinbaseScript,
-		Sequence:        wire.MaxTxInSequenceNum,
-	})
-	totalInput := CalcBlockSubsidy(blockHeight, params)
-	amountPerOutput := totalInput / uint64(numOutputs)
-	remainder := totalInput - amountPerOutput*uint64(numOutputs)
-	for i := uint32(0); i < numOutputs; i++ {
-		// Ensure the final output accounts for any remainder that might
-		// be left from splitting the input amount.
-		amount := amountPerOutput
-		if i == numOutputs-1 {
-			amount = amountPerOutput + remainder
-		}
-		tx.AddTxOut(&wire.TxOut{
-			PkScript: OpTrueScript,
-			Value:    amount,
-		})
-	}
-
-	return tx, nil
-}
-
 func TestApplyUTXOChanges(t *testing.T) {
 	// Create a new database and dag instance to run tests against.
 	dag, teardownFunc, err := DAGSetup("TestApplyUTXOChanges", Config{
@@ -857,9 +814,9 @@ func TestApplyUTXOChanges(t *testing.T) {
 		},
 	}
 
-	cbTx, err := createCoinbaseTx(1, 1, 0, dag.dagParams)
+	cbTx, err := createCoinbaseTxForTest(1, 1, 0, dag.dagParams)
 	if err != nil {
-		t.Errorf("createCoinbaseTx: %v", err)
+		t.Errorf("createCoinbaseTxForTest: %v", err)
 	}
 
 	chainedTx := wire.NewMsgTx(wire.TxVersion)
@@ -924,9 +881,9 @@ func TestDiffFromTx(t *testing.T) {
 	fus := &FullUTXOSet{
 		utxoCollection: utxoCollection{},
 	}
-	cbTx, err := createCoinbaseTx(1, 1, 0, &dagconfig.SimNetParams)
+	cbTx, err := createCoinbaseTxForTest(1, 1, 0, &dagconfig.SimNetParams)
 	if err != nil {
-		t.Errorf("createCoinbaseTx: %v", err)
+		t.Errorf("createCoinbaseTxForTest: %v", err)
 	}
 	fus.AddTx(cbTx, 1)
 	node := &blockNode{height: 2} //Fake node
diff --git a/blockdag/validate.go b/blockdag/validate.go
index 469894929..bf2b30d78 100644
--- a/blockdag/validate.go
+++ b/blockdag/validate.go
@@ -187,7 +187,7 @@ func CheckTransactionSanity(tx *util.Tx) error {
 
 	// A transaction must not exceed the maximum allowed block payload when
 	// serialized.
-	serializedTxSize := tx.MsgTx().SerializeSize()
+	serializedTxSize := msgTx.SerializeSize()
 	if serializedTxSize > wire.MaxBlockPayload {
 		str := fmt.Sprintf("serialized transaction is too big - got "+
 			"%d, max %d", serializedTxSize, wire.MaxBlockPayload)
diff --git a/mempool/mempool.go b/mempool/mempool.go
index 85a8e5bff..9ad5ceab3 100644
--- a/mempool/mempool.go
+++ b/mempool/mempool.go
@@ -657,6 +657,24 @@ func (mp *TxPool) maybeAcceptTransaction(tx *util.Tx, isNew, rateLimit, rejectDu
 		return nil, nil, err
 	}
 
+	// Check that transaction does not overuse GAS
+	msgTx := tx.MsgTx()
+	if msgTx.SubNetworkID == 0 {
+		return nil, nil, txRuleError(wire.RejectInvalid, "Subnetwork 0 is not permited in transaction")
+	} else if msgTx.SubNetworkID != wire.SubNetworkDAGCoin {
+		gasLimit, err := mp.cfg.DAG.GasLimit(msgTx.SubNetworkID)
+		if err != nil {
+			return nil, nil, err
+		}
+		if msgTx.Gas > gasLimit {
+			str := fmt.Sprintf("transaction wants more gas %v, than allowed %v",
+				msgTx.Gas, gasLimit)
+			return nil, nil, dagRuleError(blockdag.RuleError{
+				ErrorCode:   blockdag.ErrInvalidGas,
+				Description: str})
+		}
+	}
+
 	// A standalone transaction must not be a coinbase transaction.
 	if blockdag.IsCoinBase(tx) {
 		str := fmt.Sprintf("transaction %v is an individual coinbase",
diff --git a/mempool/mempool_test.go b/mempool/mempool_test.go
index b631cc9e0..1756e765d 100644
--- a/mempool/mempool_test.go
+++ b/mempool/mempool_test.go
@@ -155,11 +155,11 @@ func (p *poolHarness) CreateCoinbaseTx(blockHeight int32, numOutputs uint32) (*u
 	return util.NewTx(tx), nil
 }
 
-// CreateSignedTx creates a new signed transaction that consumes the provided
+// CreateSignedTxForSubnetwork creates a new signed transaction that consumes the provided
 // inputs and generates the provided number of outputs by evenly splitting the
 // total input amount.  All outputs will be to the payment script associated
 // with the harness and all inputs are assumed to do the same.
-func (p *poolHarness) CreateSignedTx(inputs []spendableOutpoint, numOutputs uint32) (*util.Tx, error) {
+func (p *poolHarness) CreateSignedTxForSubnetwork(inputs []spendableOutpoint, numOutputs uint32, subnetworkID uint64, gas uint64) (*util.Tx, error) {
 	// Calculate the total input amount and split it amongst the requested
 	// number of outputs.
 	var totalInput util.Amount
@@ -170,6 +170,8 @@ func (p *poolHarness) CreateSignedTx(inputs []spendableOutpoint, numOutputs uint
 	remainder := uint64(totalInput) - amountPerOutput*uint64(numOutputs)
 
 	tx := wire.NewMsgTx(wire.TxVersion)
+	tx.SubNetworkID = subnetworkID
+	tx.Gas = gas
 	for _, input := range inputs {
 		tx.AddTxIn(&wire.TxIn{
 			PreviousOutPoint: input.outPoint,
@@ -203,6 +205,14 @@ func (p *poolHarness) CreateSignedTx(inputs []spendableOutpoint, numOutputs uint
 	return util.NewTx(tx), nil
 }
 
+// CreateSignedTx creates a new signed transaction that consumes the provided
+// inputs and generates the provided number of outputs by evenly splitting the
+// total input amount.  All outputs will be to the payment script associated
+// with the harness and all inputs are assumed to do the same.
+func (p *poolHarness) CreateSignedTx(inputs []spendableOutpoint, numOutputs uint32) (*util.Tx, error) {
+	return p.CreateSignedTxForSubnetwork(inputs, numOutputs, wire.SubNetworkDAGCoin, 0)
+}
+
 // CreateTxChain creates a chain of zero-fee transactions (each subsequent
 // transaction spends the entire amount from the previous one) with the first
 // one spending the provided outpoint.  Each transaction spends the entire
@@ -248,12 +258,12 @@ func (p *poolHarness) CreateTxChain(firstOutput spendableOutpoint, numTxns uint3
 // for testing.  Also, the fake chain is populated with the returned spendable
 // outputs so the caller can easily create new valid transactions which build
 // off of it.
-func newPoolHarness(dagParams *dagconfig.Params, numOutputs uint32, dbName string) (*poolHarness, []spendableOutpoint, error) {
+func newPoolHarness(dagParams *dagconfig.Params, numOutputs uint32, dbName string) (*poolHarness, []spendableOutpoint, func(), error) {
 	// Use a hard coded key pair for deterministic results.
 	keyBytes, err := hex.DecodeString("700868df1838811ffbdf918fb482c1f7e" +
 		"ad62db4b97bd7012c23e726485e577d")
 	if err != nil {
-		return nil, nil, err
+		return nil, nil, nil, err
 	}
 	signKey, signPub := btcec.PrivKeyFromBytes(btcec.S256(), keyBytes)
 
@@ -262,12 +272,12 @@ func newPoolHarness(dagParams *dagconfig.Params, numOutputs uint32, dbName strin
 	pubKeyBytes := signPub.SerializeCompressed()
 	payPubKeyAddr, err := util.NewAddressPubKey(pubKeyBytes, dagParams.Prefix)
 	if err != nil {
-		return nil, nil, err
+		return nil, nil, nil, err
 	}
 	payAddr := payPubKeyAddr.AddressPubKeyHash()
 	pkScript, err := txscript.PayToAddrScript(payAddr)
 	if err != nil {
-		return nil, nil, err
+		return nil, nil, nil, err
 	}
 
 	// Create a new database and chain instance to run tests against.
@@ -275,9 +285,13 @@ func newPoolHarness(dagParams *dagconfig.Params, numOutputs uint32, dbName strin
 		DAGParams: &dagconfig.MainNetParams,
 	})
 	if err != nil {
-		return nil, nil, fmt.Errorf("Failed to setup DAG instance: %v", err)
+		return nil, nil, nil, fmt.Errorf("Failed to setup DAG instance: %v", err)
 	}
-	defer teardownFunc()
+	defer func() {
+		if err != nil {
+			teardownFunc()
+		}
+	}()
 
 	// Create a new fake chain and harness bound to it.
 	chain := &fakeChain{}
@@ -317,7 +331,7 @@ func newPoolHarness(dagParams *dagconfig.Params, numOutputs uint32, dbName strin
 	curHeight := harness.chain.BestHeight()
 	coinbase, err := harness.CreateCoinbaseTx(curHeight+1, numOutputs)
 	if err != nil {
-		return nil, nil, err
+		return nil, nil, nil, err
 	}
 	harness.txPool.mpUTXOSet.AddTx(coinbase.MsgTx(), curHeight+1)
 	for i := uint32(0); i < numOutputs; i++ {
@@ -326,7 +340,7 @@ func newPoolHarness(dagParams *dagconfig.Params, numOutputs uint32, dbName strin
 	harness.chain.SetHeight(int32(dagParams.CoinbaseMaturity) + curHeight)
 	harness.chain.SetMedianTimePast(time.Now())
 
-	return &harness, outpoints, nil
+	return &harness, outpoints, teardownFunc, nil
 }
 
 // testContext houses a test-related state that is useful to pass to helper
@@ -434,10 +448,11 @@ func (p *poolHarness) createTx(outpoint spendableOutpoint, fee uint64, numOutput
 }
 
 func TestProcessTransaction(t *testing.T) {
-	harness, spendableOuts, err := newPoolHarness(&dagconfig.MainNetParams, 6, "TestProcessTransaction")
+	harness, spendableOuts, teardownFunc, err := newPoolHarness(&dagconfig.MainNetParams, 6, "TestProcessTransaction")
 	if err != nil {
 		t.Fatalf("unable to create test pool: %v", err)
 	}
+	defer teardownFunc()
 	tc := &testContext{t, harness}
 
 	//Checks that a transaction cannot be added to the transaction pool if it's already there
@@ -593,7 +608,8 @@ func TestProcessTransaction(t *testing.T) {
 			Value:    5000000000,
 			PkScript: p2shPKScript,
 		}},
-		LockTime: 0,
+		LockTime:     0,
+		SubNetworkID: wire.SubNetworkDAGCoin,
 	})
 	harness.txPool.mpUTXOSet.AddTx(p2shTx.MsgTx(), curHeight+1)
 
@@ -608,7 +624,8 @@ func TestProcessTransaction(t *testing.T) {
 			Value:    5000000000,
 			PkScript: dummyPkScript,
 		}},
-		LockTime: 0,
+		LockTime:     0,
+		SubNetworkID: wire.SubNetworkDAGCoin,
 	})
 	_, err = harness.txPool.ProcessTransaction(nonStdSigScriptTx, true, false, 0)
 	if err == nil {
@@ -651,8 +668,9 @@ func TestProcessTransaction(t *testing.T) {
 			SignatureScript:  dummySigScript,
 			Sequence:         wire.MaxTxInSequenceNum,
 		}},
-		TxOut:    []*wire.TxOut{},
-		LockTime: 0,
+		TxOut:        []*wire.TxOut{},
+		LockTime:     0,
+		SubNetworkID: wire.SubNetworkDAGCoin,
 	})
 	_, err = harness.txPool.ProcessTransaction(noOutsTx, true, false, 0)
 	if err == nil {
@@ -728,7 +746,8 @@ func TestProcessTransaction(t *testing.T) {
 			Value:    1,
 			PkScript: dummyPkScript,
 		}},
-		LockTime: 0,
+		LockTime:     0,
+		SubNetworkID: wire.SubNetworkDAGCoin,
 	})
 	_, err = harness.txPool.ProcessTransaction(tx, true, false, 0)
 	fmt.Println(err)
@@ -738,14 +757,14 @@ func TestProcessTransaction(t *testing.T) {
 	if code, _ := extractRejectCode(err); code != wire.RejectNonstandard {
 		t.Errorf("Unexpected error code. Expected %v but got %v", wire.RejectNonstandard, code)
 	}
-
 }
 
 func TestAddrIndex(t *testing.T) {
-	harness, spendableOuts, err := newPoolHarness(&dagconfig.MainNetParams, 2, "TestAddrIndex")
+	harness, spendableOuts, teardownFunc, err := newPoolHarness(&dagconfig.MainNetParams, 2, "TestAddrIndex")
 	if err != nil {
 		t.Fatalf("unable to create test pool: %v", err)
 	}
+	defer teardownFunc()
 	harness.txPool.cfg.AddrIndex = &indexers.AddrIndex{}
 	enteredAddUnconfirmedTx := false
 	guard := monkey.Patch((*indexers.AddrIndex).AddUnconfirmedTx, func(idx *indexers.AddrIndex, tx *util.Tx, utxoSet blockdag.UTXOSet) {
@@ -782,10 +801,11 @@ func TestAddrIndex(t *testing.T) {
 }
 
 func TestFeeEstimatorCfg(t *testing.T) {
-	harness, spendableOuts, err := newPoolHarness(&dagconfig.MainNetParams, 2, "TestFeeEstimatorCfg")
+	harness, spendableOuts, teardownFunc, err := newPoolHarness(&dagconfig.MainNetParams, 2, "TestFeeEstimatorCfg")
 	if err != nil {
 		t.Fatalf("unable to create test pool: %v", err)
 	}
+	defer teardownFunc()
 	harness.txPool.cfg.FeeEstimator = &FeeEstimator{}
 	enteredObserveTransaction := false
 	guard := monkey.Patch((*FeeEstimator).ObserveTransaction, func(ef *FeeEstimator, t *TxDesc) {
@@ -808,10 +828,11 @@ func TestFeeEstimatorCfg(t *testing.T) {
 }
 
 func TestDoubleSpends(t *testing.T) {
-	harness, spendableOuts, err := newPoolHarness(&dagconfig.MainNetParams, 2, "TestDoubleSpends")
+	harness, spendableOuts, teardownFunc, err := newPoolHarness(&dagconfig.MainNetParams, 2, "TestDoubleSpends")
 	if err != nil {
 		t.Fatalf("unable to create test pool: %v", err)
 	}
+	defer teardownFunc()
 	tc := &testContext{t, harness}
 
 	//Add two transactions to the mempool
@@ -857,7 +878,11 @@ func TestDoubleSpends(t *testing.T) {
 //TestFetchTransaction checks that FetchTransaction
 //returns only transaction from the main pool and not from the orphan pool
 func TestFetchTransaction(t *testing.T) {
-	harness, spendableOuts, err := newPoolHarness(&dagconfig.MainNetParams, 1, "TestFetchTransaction")
+	harness, spendableOuts, teardownFunc, err := newPoolHarness(&dagconfig.MainNetParams, 1, "TestFetchTransaction")
+	if err != nil {
+		t.Fatalf("unable to create test pool: %v", err)
+	}
+	defer teardownFunc()
 	tc := &testContext{t, harness}
 
 	orphanedTx, err := harness.CreateSignedTx([]spendableOutpoint{{
@@ -899,10 +924,11 @@ func TestFetchTransaction(t *testing.T) {
 // they are all orphans.  Finally, it adds the linking transaction and ensures
 // the entire orphan chain is moved to the transaction pool.
 func TestSimpleOrphanChain(t *testing.T) {
-	harness, spendableOuts, err := newPoolHarness(&dagconfig.MainNetParams, 1, "TestSimpleOrphanChain")
+	harness, spendableOuts, teardownFunc, err := newPoolHarness(&dagconfig.MainNetParams, 1, "TestSimpleOrphanChain")
 	if err != nil {
 		t.Fatalf("unable to create test pool: %v", err)
 	}
+	defer teardownFunc()
 	tc := &testContext{t, harness}
 
 	// Create a chain of transactions rooted with the first spendable output
@@ -960,10 +986,11 @@ func TestSimpleOrphanChain(t *testing.T) {
 // TestOrphanReject ensures that orphans are properly rejected when the allow
 // orphans flag is not set on ProcessTransaction.
 func TestOrphanReject(t *testing.T) {
-	harness, outputs, err := newPoolHarness(&dagconfig.MainNetParams, 1, "TestOrphanReject")
+	harness, outputs, teardownFunc, err := newPoolHarness(&dagconfig.MainNetParams, 1, "TestOrphanReject")
 	if err != nil {
 		t.Fatalf("unable to create test pool: %v", err)
 	}
+	defer teardownFunc()
 	tc := &testContext{t, harness}
 
 	// Create a chain of transactions rooted with the first spendable output
@@ -1014,10 +1041,11 @@ func TestOrphanReject(t *testing.T) {
 // it will check if we are beyond nextExpireScan, and if so, it will remove
 // all expired orphan transactions
 func TestOrphanExpiration(t *testing.T) {
-	harness, _, err := newPoolHarness(&dagconfig.MainNetParams, 1, "TestOrphanExpiration")
+	harness, _, teardownFunc, err := newPoolHarness(&dagconfig.MainNetParams, 1, "TestOrphanExpiration")
 	if err != nil {
 		t.Fatalf("unable to create test pool: %v", err)
 	}
+	defer teardownFunc()
 	tc := &testContext{t, harness}
 
 	expiredTx, err := harness.CreateSignedTx([]spendableOutpoint{{
@@ -1058,10 +1086,11 @@ func TestOrphanExpiration(t *testing.T) {
 //TestMaxOrphanTxSize ensures that a transaction that is
 //bigger than MaxOrphanTxSize will get rejected
 func TestMaxOrphanTxSize(t *testing.T) {
-	harness, _, err := newPoolHarness(&dagconfig.MainNetParams, 1, "TestMaxOrphanTxSize")
+	harness, _, teardownFunc, err := newPoolHarness(&dagconfig.MainNetParams, 1, "TestMaxOrphanTxSize")
 	if err != nil {
 		t.Fatalf("unable to create test pool: %v", err)
 	}
+	defer teardownFunc()
 	tc := &testContext{t, harness}
 	harness.txPool.cfg.Policy.MaxOrphanTxSize = 1
 
@@ -1085,10 +1114,11 @@ func TestMaxOrphanTxSize(t *testing.T) {
 }
 
 func TestRemoveTransaction(t *testing.T) {
-	harness, outputs, err := newPoolHarness(&dagconfig.MainNetParams, 1, "TestRemoveTransaction")
+	harness, outputs, teardownFunc, err := newPoolHarness(&dagconfig.MainNetParams, 1, "TestRemoveTransaction")
 	if err != nil {
 		t.Fatalf("unable to create test pool: %v", err)
 	}
+	defer teardownFunc()
 	tc := &testContext{t, harness}
 	chainedTxns, err := harness.CreateTxChain(outputs[0], 5)
 	if err != nil {
@@ -1130,10 +1160,11 @@ func TestRemoveTransaction(t *testing.T) {
 // TestOrphanEviction ensures that exceeding the maximum number of orphans
 // evicts entries to make room for the new ones.
 func TestOrphanEviction(t *testing.T) {
-	harness, outputs, err := newPoolHarness(&dagconfig.MainNetParams, 1, "TestOrphanEviction")
+	harness, outputs, teardownFunc, err := newPoolHarness(&dagconfig.MainNetParams, 1, "TestOrphanEviction")
 	if err != nil {
 		t.Fatalf("unable to create test pool: %v", err)
 	}
+	defer teardownFunc()
 	tc := &testContext{t, harness}
 
 	// Create a chain of transactions rooted with the first spendable output
@@ -1191,10 +1222,11 @@ func TestOrphanEviction(t *testing.T) {
 // Attempt to remove orphans by tag,
 // and ensure the state of all other orphans are unaffected.
 func TestRemoveOrphansByTag(t *testing.T) {
-	harness, _, err := newPoolHarness(&dagconfig.MainNetParams, 1, "TestRemoveOrphansByTag")
+	harness, _, teardownFunc, err := newPoolHarness(&dagconfig.MainNetParams, 1, "TestRemoveOrphansByTag")
 	if err != nil {
 		t.Fatalf("unable to create test pool: %v", err)
 	}
+	defer teardownFunc()
 	tc := &testContext{t, harness}
 
 	orphanedTx1, err := harness.CreateSignedTx([]spendableOutpoint{{
@@ -1247,10 +1279,11 @@ func TestRemoveOrphansByTag(t *testing.T) {
 // redeems it and when there is not.
 func TestBasicOrphanRemoval(t *testing.T) {
 	const maxOrphans = 4
-	harness, spendableOuts, err := newPoolHarness(&dagconfig.MainNetParams, 1, "TestBasicOrphanRemoval")
+	harness, spendableOuts, teardownFunc, err := newPoolHarness(&dagconfig.MainNetParams, 1, "TestBasicOrphanRemoval")
 	if err != nil {
 		t.Fatalf("unable to create test pool: %v", err)
 	}
+	defer teardownFunc()
 	harness.txPool.cfg.Policy.MaxOrphanTxs = maxOrphans
 	tc := &testContext{t, harness}
 
@@ -1320,10 +1353,11 @@ func TestBasicOrphanRemoval(t *testing.T) {
 // from other orphans) are removed as expected.
 func TestOrphanChainRemoval(t *testing.T) {
 	const maxOrphans = 10
-	harness, spendableOuts, err := newPoolHarness(&dagconfig.MainNetParams, 1, "TestOrphanChainRemoval")
+	harness, spendableOuts, teardownFunc, err := newPoolHarness(&dagconfig.MainNetParams, 1, "TestOrphanChainRemoval")
 	if err != nil {
 		t.Fatalf("unable to create test pool: %v", err)
 	}
+	defer teardownFunc()
 	harness.txPool.cfg.Policy.MaxOrphanTxs = maxOrphans
 	tc := &testContext{t, harness}
 
@@ -1381,10 +1415,11 @@ func TestOrphanChainRemoval(t *testing.T) {
 // output that is spend by another transaction entering the pool are removed.
 func TestMultiInputOrphanDoubleSpend(t *testing.T) {
 	const maxOrphans = 4
-	harness, outputs, err := newPoolHarness(&dagconfig.MainNetParams, 1, "TestMultiInputOrphanDoubleSpend")
+	harness, outputs, teardownFunc, err := newPoolHarness(&dagconfig.MainNetParams, 1, "TestMultiInputOrphanDoubleSpend")
 	if err != nil {
 		t.Fatalf("unable to create test pool: %v", err)
 	}
+	defer teardownFunc()
 	harness.txPool.cfg.Policy.MaxOrphanTxs = maxOrphans
 	tc := &testContext{t, harness}
 
@@ -1467,10 +1502,11 @@ func TestMultiInputOrphanDoubleSpend(t *testing.T) {
 // TestCheckSpend tests that CheckSpend returns the expected spends found in
 // the mempool.
 func TestCheckSpend(t *testing.T) {
-	harness, outputs, err := newPoolHarness(&dagconfig.MainNetParams, 1, "TestCheckSpend")
+	harness, outputs, teardownFunc, err := newPoolHarness(&dagconfig.MainNetParams, 1, "TestCheckSpend")
 	if err != nil {
 		t.Fatalf("unable to create test pool: %v", err)
 	}
+	defer teardownFunc()
 
 	// The mempool is empty, so none of the spendable outputs should have a
 	// spend there.
@@ -1532,10 +1568,11 @@ func TestCheckSpend(t *testing.T) {
 }
 
 func TestCount(t *testing.T) {
-	harness, outputs, err := newPoolHarness(&dagconfig.MainNetParams, 1, "TestCount")
+	harness, outputs, teardownFunc, err := newPoolHarness(&dagconfig.MainNetParams, 1, "TestCount")
 	if err != nil {
 		t.Fatalf("unable to create test pool: %v", err)
 	}
+	defer teardownFunc()
 	if harness.txPool.Count() != 0 {
 		t.Errorf("TestCount: txPool should be initialized with 0 transactions")
 	}
@@ -1641,10 +1678,11 @@ func TestExtractRejectCode(t *testing.T) {
 
 // TestHandleNewBlock
 func TestHandleNewBlock(t *testing.T) {
-	harness, spendableOuts, err := newPoolHarness(&dagconfig.MainNetParams, 2, "TestHandleNewBlock")
+	harness, spendableOuts, teardownFunc, err := newPoolHarness(&dagconfig.MainNetParams, 2, "TestHandleNewBlock")
 	if err != nil {
 		t.Fatalf("unable to create test pool: %v", err)
 	}
+	defer teardownFunc()
 	tc := &testContext{t, harness}
 
 	// Create parent transaction for orphan transaction below
@@ -1790,7 +1828,43 @@ var dummyBlock = wire.MsgBlock{
 					},
 				},
 			},
-			LockTime: 0,
+			LockTime:     0,
+			SubNetworkID: wire.SubNetworkDAGCoin,
 		},
 	},
 }
+
+func TestTransactionGas(t *testing.T) {
+	harness, spendableOuts, teardownFunc, err := newPoolHarness(&dagconfig.MainNetParams, 6, "TestTransactionGas")
+	if err != nil {
+		t.Fatalf("unable to create test pool: %v", err)
+	}
+	defer teardownFunc()
+	//	tc := &testContext{t, harness}
+
+	const gasLimit = 10000
+	subnetworkID, err := blockdag.RegisterSubnetworkForTest(harness.txPool.cfg.DAG, gasLimit)
+	if err != nil {
+		t.Fatalf("unable to register network: %v", err)
+	}
+
+	// Create valid transaction
+	tx, err := harness.CreateSignedTxForSubnetwork(spendableOuts[:1], 1, subnetworkID, gasLimit)
+	if err != nil {
+		t.Fatalf("unable to create transaction: %v", err)
+	}
+	_, err = harness.txPool.ProcessTransaction(tx, true, false, 0)
+	if err != nil {
+		t.Errorf("ProcessTransaction: unexpected error: %v", err)
+	}
+
+	// Create invalid transaction
+	tx, err = harness.CreateSignedTxForSubnetwork(spendableOuts[1:], 1, subnetworkID, gasLimit+1)
+	if err != nil {
+		t.Fatalf("unable to create transaction: %v", err)
+	}
+	_, err = harness.txPool.ProcessTransaction(tx, true, false, 0)
+	if err == nil {
+		t.Error("ProcessTransaction did not return error, expecting ErrInvalidGas")
+	}
+}
diff --git a/mining/mining.go b/mining/mining.go
index 8ff4e1172..f181ae100 100644
--- a/mining/mining.go
+++ b/mining/mining.go
@@ -482,7 +482,7 @@ func (g *BlkTmplGenerator) NewBlockTemplate(payToAddress util.Address) (*BlockTe
 		prioItem := heap.Pop(priorityQueue).(*txPrioItem)
 		tx := prioItem.tx
 
-		if tx.MsgTx().SubNetworkID > wire.SubNetworkDAGCoin {
+		if tx.MsgTx().SubNetworkID != wire.SubNetworkDAGCoin {
 			subnetwork := tx.MsgTx().SubNetworkID
 			gasUsage, ok := gasUsageMap[subnetwork]
 			if !ok {