diff --git a/pkg/core/blockchain.go b/pkg/core/blockchain.go
index b59f177e3..0ef370b8f 100644
--- a/pkg/core/blockchain.go
+++ b/pkg/core/blockchain.go
@@ -723,7 +723,7 @@ func (bc *Blockchain) storeBlock(block *block.Block) error {
 	bc.topBlock.Store(block)
 	atomic.StoreUint32(&bc.blockHeight, block.Index)
 	updateBlockHeightMetric(block.Index)
-	bc.memPool.RemoveStale(bc.isTxStillRelevant)
+	bc.memPool.RemoveStale(bc.isTxStillRelevant, bc)
 	return nil
 }
 
@@ -817,6 +817,11 @@ func (bc *Blockchain) GetNEP5Balances(acc util.Uint160) *state.NEP5Balances {
 	return bs
 }
 
+// GetUtilityTokenBalance returns utility token (GAS) balance for the acc.
+func (bc *Blockchain) GetUtilityTokenBalance(acc util.Uint160) util.Fixed8 {
+	return util.Fixed8FromInt64(bc.GetNEP5Balances(acc).Trackers[bc.contracts.GAS.Hash].Balance)
+}
+
 // LastBatch returns last persisted storage batch.
 func (bc *Blockchain) LastBatch() *storage.MemBatch {
 	return bc.lastBatch
@@ -1171,7 +1176,7 @@ func (bc *Blockchain) verifyTx(t *transaction.Transaction, block *block.Block) e
 	if t.ValidUntilBlock <= height || t.ValidUntilBlock > height+transaction.MaxValidUntilBlockIncrement {
 		return errors.Errorf("transaction has expired. ValidUntilBlock = %d, current height = %d", t.ValidUntilBlock, height)
 	}
-	balance := util.Fixed8FromInt64(bc.GetNEP5Balances(t.Sender).Trackers[bc.contracts.GAS.Hash].Balance)
+	balance := bc.GetUtilityTokenBalance(t.Sender)
 	need := t.SystemFee.Add(t.NetworkFee)
 	if balance.LessThan(need) {
 		return errors.Errorf("insufficient funds: balance is %v, need: %v", balance, need)
@@ -1189,7 +1194,7 @@ func (bc *Blockchain) verifyTx(t *transaction.Transaction, block *block.Block) e
 		return errors.New("invalid transaction's inputs")
 	}
 	if block == nil {
-		if ok := bc.memPool.Verify(t); !ok {
+		if ok := bc.memPool.Verify(t, bc); !ok {
 			return errors.New("invalid transaction due to conflicts with the memory pool")
 		}
 	}
diff --git a/pkg/core/mempool/feer.go b/pkg/core/mempool/feer.go
index e72b9f480..91d81e4e8 100644
--- a/pkg/core/mempool/feer.go
+++ b/pkg/core/mempool/feer.go
@@ -8,4 +8,5 @@ import (
 type Feer interface {
 	IsLowPriority(util.Fixed8) bool
 	FeePerByte() util.Fixed8
+	GetUtilityTokenBalance(util.Uint160) util.Fixed8
 }
diff --git a/pkg/core/mempool/mem_pool.go b/pkg/core/mempool/mem_pool.go
index 725c2af45..bd566936a 100644
--- a/pkg/core/mempool/mem_pool.go
+++ b/pkg/core/mempool/mem_pool.go
@@ -39,6 +39,13 @@ type TxWithFee struct {
 	Fee util.Fixed8
 }
 
+// utilityBalanceAndFees stores sender's balance and overall fees of
+// sender's transactions which are currently in mempool
+type utilityBalanceAndFees struct {
+	balance util.Fixed8
+	feeSum  util.Fixed8
+}
+
 // Pool stores the unconfirms transactions.
 type Pool struct {
 	lock         sync.RWMutex
@@ -46,6 +53,7 @@ type Pool struct {
 	verifiedTxes items
 	inputs       []*transaction.Input
 	claims       []*transaction.Input
+	fees         map[util.Uint160]utilityBalanceAndFees
 
 	capacity int
 }
@@ -156,6 +164,38 @@ func dropInputFromSortedSlice(slice *[]*transaction.Input, input *transaction.In
 	*slice = (*slice)[:len(*slice)-1]
 }
 
+// tryAddSendersFee tries to add system fee and network fee to the total sender`s fee in mempool
+// and returns false if sender has not enough GAS to pay
+func (mp *Pool) tryAddSendersFee(tx *transaction.Transaction, feer Feer) bool {
+	if !mp.checkBalanceAndUpdate(tx, feer) {
+		return false
+	}
+	mp.addSendersFee(tx)
+	return true
+}
+
+// checkBalanceAndUpdate returns true in case when sender has enough GAS to pay for
+// the transaction and sets sender's balance value in mempool in case if it was not set
+func (mp *Pool) checkBalanceAndUpdate(tx *transaction.Transaction, feer Feer) bool {
+	senderFee, ok := mp.fees[tx.Sender]
+	if !ok {
+		senderFee.balance = feer.GetUtilityTokenBalance(tx.Sender)
+		mp.fees[tx.Sender] = senderFee
+	}
+	needFee := senderFee.feeSum + tx.SystemFee + tx.NetworkFee
+	if senderFee.balance < needFee {
+		return false
+	}
+	return true
+}
+
+// addSendersFee adds system fee and network fee to the total sender`s fee in mempool
+func (mp *Pool) addSendersFee(tx *transaction.Transaction) {
+	senderFee := mp.fees[tx.Sender]
+	senderFee.feeSum += tx.SystemFee + tx.NetworkFee
+	mp.fees[tx.Sender] = senderFee
+}
+
 // Add tries to add given transaction to the Pool.
 func (mp *Pool) Add(t *transaction.Transaction, fee Feer) error {
 	var pItem = &item{
@@ -164,7 +204,7 @@ func (mp *Pool) Add(t *transaction.Transaction, fee Feer) error {
 	}
 	pItem.isLowPrio = fee.IsLowPriority(pItem.txn.NetworkFee)
 	mp.lock.Lock()
-	if !mp.checkTxConflicts(t) {
+	if !mp.checkTxConflicts(t, fee) {
 		mp.lock.Unlock()
 		return ErrConflict
 	}
@@ -202,6 +242,7 @@ func (mp *Pool) Add(t *transaction.Transaction, fee Feer) error {
 		copy(mp.verifiedTxes[n+1:], mp.verifiedTxes[n:])
 		mp.verifiedTxes[n] = pItem
 	}
+	mp.addSendersFee(pItem.txn)
 
 	// For lots of inputs it might be easier to push them all and sort
 	// afterwards, but that requires benchmarking.
@@ -237,6 +278,9 @@ func (mp *Pool) Remove(hash util.Uint256) {
 		} else if num == len(mp.verifiedTxes)-1 {
 			mp.verifiedTxes = mp.verifiedTxes[:num]
 		}
+		senderFee := mp.fees[it.txn.Sender]
+		senderFee.feeSum -= it.txn.SystemFee + it.txn.NetworkFee
+		mp.fees[it.txn.Sender] = senderFee
 		for i := range it.txn.Inputs {
 			dropInputFromSortedSlice(&mp.inputs, &it.txn.Inputs[i])
 		}
@@ -254,15 +298,16 @@ func (mp *Pool) Remove(hash util.Uint256) {
 // RemoveStale filters verified transactions through the given function keeping
 // only the transactions for which it returns a true result. It's used to quickly
 // drop part of the mempool that is now invalid after the block acceptance.
-func (mp *Pool) RemoveStale(isOK func(*transaction.Transaction) bool) {
+func (mp *Pool) RemoveStale(isOK func(*transaction.Transaction) bool, feer Feer) {
 	mp.lock.Lock()
 	// We can reuse already allocated slice
 	// because items are iterated one-by-one in increasing order.
 	newVerifiedTxes := mp.verifiedTxes[:0]
 	newInputs := mp.inputs[:0]
 	newClaims := mp.claims[:0]
+	mp.fees = make(map[util.Uint160]utilityBalanceAndFees) // it'd be nice to reuse existing map, but we can't easily clear it
 	for _, itm := range mp.verifiedTxes {
-		if isOK(itm.txn) {
+		if isOK(itm.txn) && mp.tryAddSendersFee(itm.txn, feer) {
 			newVerifiedTxes = append(newVerifiedTxes, itm)
 			for i := range itm.txn.Inputs {
 				newInputs = append(newInputs, &itm.txn.Inputs[i])
@@ -295,6 +340,7 @@ func NewMemPool(capacity int) Pool {
 		verifiedMap:  make(map[util.Uint256]*item),
 		verifiedTxes: make([]*item, 0, capacity),
 		capacity:     capacity,
+		fees:         make(map[util.Uint160]utilityBalanceAndFees),
 	}
 }
 
@@ -338,10 +384,13 @@ func areInputsInPool(inputs []transaction.Input, pool []*transaction.Input) bool
 }
 
 // checkTxConflicts is an internal unprotected version of Verify.
-func (mp *Pool) checkTxConflicts(tx *transaction.Transaction) bool {
+func (mp *Pool) checkTxConflicts(tx *transaction.Transaction, fee Feer) bool {
 	if areInputsInPool(tx.Inputs, mp.inputs) {
 		return false
 	}
+	if !mp.checkBalanceAndUpdate(tx, fee) {
+		return false
+	}
 	switch tx.Type {
 	case transaction.ClaimType:
 		claim := tx.Data.(*transaction.ClaimTX)
@@ -364,8 +413,8 @@ func (mp *Pool) checkTxConflicts(tx *transaction.Transaction) bool {
 // Verify verifies if the inputs of a transaction tx are already used in any other transaction in the memory pool.
 // If yes, the transaction tx is not a valid transaction and the function return false.
 // If no, the transaction tx is a valid transaction and the function return true.
-func (mp *Pool) Verify(tx *transaction.Transaction) bool {
+func (mp *Pool) Verify(tx *transaction.Transaction, feer Feer) bool {
 	mp.lock.RLock()
 	defer mp.lock.RUnlock()
-	return mp.checkTxConflicts(tx)
+	return mp.checkTxConflicts(tx, feer)
 }
diff --git a/pkg/core/mempool/mem_pool_test.go b/pkg/core/mempool/mem_pool_test.go
index d0c3f3a9f..c4dbfec75 100644
--- a/pkg/core/mempool/mem_pool_test.go
+++ b/pkg/core/mempool/mem_pool_test.go
@@ -24,6 +24,10 @@ func (fs *FeerStub) FeePerByte() util.Fixed8 {
 	return fs.feePerByte
 }
 
+func (fs *FeerStub) GetUtilityTokenBalance(uint160 util.Uint160) util.Fixed8 {
+	return util.Fixed8FromInt64(10000)
+}
+
 func testMemPoolAddRemoveWithFeer(t *testing.T, fs Feer) {
 	mp := NewMemPool(10)
 	tx := transaction.NewContractTX()
@@ -111,7 +115,7 @@ func TestMemPoolAddRemoveWithInputsAndClaims(t *testing.T) {
 			return false
 		}
 		return true
-	})
+	}, &FeerStub{})
 	assert.Equal(t, len(txm1.Inputs), len(mp.inputs))
 	assert.True(t, sort.SliceIsSorted(mp.inputs, mpLessInputs))
 	assert.Equal(t, len(claim2.Claims), len(mp.claims))
@@ -124,24 +128,24 @@ func TestMemPoolVerifyInputs(t *testing.T) {
 	tx.Nonce = 1
 	inhash1 := random.Uint256()
 	tx.Inputs = append(tx.Inputs, transaction.Input{PrevHash: inhash1, PrevIndex: 0})
-	require.Equal(t, true, mp.Verify(tx))
+	require.Equal(t, true, mp.Verify(tx, &FeerStub{}))
 	require.NoError(t, mp.Add(tx, &FeerStub{}))
 
 	tx2 := transaction.NewContractTX()
 	tx2.Nonce = 2
 	inhash2 := random.Uint256()
 	tx2.Inputs = append(tx2.Inputs, transaction.Input{PrevHash: inhash2, PrevIndex: 0})
-	require.Equal(t, true, mp.Verify(tx2))
+	require.Equal(t, true, mp.Verify(tx2, &FeerStub{}))
 	require.NoError(t, mp.Add(tx2, &FeerStub{}))
 
 	tx3 := transaction.NewContractTX()
 	tx3.Nonce = 3
 	// Different index number, but the same PrevHash as in tx1.
 	tx3.Inputs = append(tx3.Inputs, transaction.Input{PrevHash: inhash1, PrevIndex: 1})
-	require.Equal(t, true, mp.Verify(tx3))
+	require.Equal(t, true, mp.Verify(tx3, &FeerStub{}))
 	// The same input as in tx2.
 	tx3.Inputs = append(tx3.Inputs, transaction.Input{PrevHash: inhash2, PrevIndex: 0})
-	require.Equal(t, false, mp.Verify(tx3))
+	require.Equal(t, false, mp.Verify(tx3, &FeerStub{}))
 	require.Error(t, mp.Add(tx3, &FeerStub{}))
 }
 
@@ -156,30 +160,30 @@ func TestMemPoolVerifyClaims(t *testing.T) {
 		claim1.Claims = append(claim1.Claims, transaction.Input{PrevHash: hash1, PrevIndex: uint16(i)})
 		claim1.Claims = append(claim1.Claims, transaction.Input{PrevHash: hash2, PrevIndex: uint16(i)})
 	}
-	require.Equal(t, true, mp.Verify(tx1))
+	require.Equal(t, true, mp.Verify(tx1, &FeerStub{}))
 	require.NoError(t, mp.Add(tx1, &FeerStub{}))
 
 	tx2, claim2 := newClaimTX()
 	for i := 0; i < 10; i++ {
 		claim2.Claims = append(claim2.Claims, transaction.Input{PrevHash: hash2, PrevIndex: uint16(i + 10)})
 	}
-	require.Equal(t, true, mp.Verify(tx2))
+	require.Equal(t, true, mp.Verify(tx2, &FeerStub{}))
 	require.NoError(t, mp.Add(tx2, &FeerStub{}))
 
 	tx3, claim3 := newClaimTX()
 	claim3.Claims = append(claim3.Claims, transaction.Input{PrevHash: hash1, PrevIndex: 0})
-	require.Equal(t, false, mp.Verify(tx3))
+	require.Equal(t, false, mp.Verify(tx3, &FeerStub{}))
 	require.Error(t, mp.Add(tx3, &FeerStub{}))
 }
 
 func TestMemPoolVerifyIssue(t *testing.T) {
 	mp := NewMemPool(50)
 	tx1 := newIssueTX()
-	require.Equal(t, true, mp.Verify(tx1))
+	require.Equal(t, true, mp.Verify(tx1, &FeerStub{}))
 	require.NoError(t, mp.Add(tx1, &FeerStub{}))
 
 	tx2 := newIssueTX()
-	require.Equal(t, false, mp.Verify(tx2))
+	require.Equal(t, false, mp.Verify(tx2, &FeerStub{}))
 	require.Error(t, mp.Add(tx2, &FeerStub{}))
 }
 
@@ -335,7 +339,7 @@ func TestRemoveStale(t *testing.T) {
 			}
 		}
 		return false
-	})
+	}, &FeerStub{})
 	require.Equal(t, mempoolSize/2, mp.Count())
 	verTxes := mp.GetVerifiedTransactions()
 	for _, txf := range verTxes {
@@ -343,3 +347,76 @@ func TestRemoveStale(t *testing.T) {
 		require.Contains(t, txes2, txf.Tx)
 	}
 }
+
+func TestMemPoolFees(t *testing.T) {
+	mp := NewMemPool(10)
+	sender0 := util.Uint160{1, 2, 3}
+	tx0 := transaction.NewContractTX()
+	tx0.NetworkFee = util.Fixed8FromInt64(11000)
+	tx0.Sender = sender0
+	// insufficient funds to add transaction, but balance should be stored
+	require.Equal(t, false, mp.Verify(tx0, &FeerStub{}))
+	require.Error(t, mp.Add(tx0, &FeerStub{}))
+	require.Equal(t, 1, len(mp.fees))
+	require.Equal(t, utilityBalanceAndFees{
+		balance: util.Fixed8FromInt64(10000),
+		feeSum:  0,
+	}, mp.fees[sender0])
+
+	// no problems with adding another transaction with lower fee
+	tx1 := transaction.NewContractTX()
+	tx1.NetworkFee = util.Fixed8FromInt64(7000)
+	tx1.Sender = sender0
+	require.NoError(t, mp.Add(tx1, &FeerStub{}))
+	require.Equal(t, 1, len(mp.fees))
+	require.Equal(t, utilityBalanceAndFees{
+		balance: util.Fixed8FromInt64(10000),
+		feeSum:  util.Fixed8FromInt64(7000),
+	}, mp.fees[sender0])
+
+	// balance shouldn't change after adding one more transaction
+	tx2 := transaction.NewContractTX()
+	tx2.NetworkFee = util.Fixed8FromFloat(3000)
+	tx2.Sender = sender0
+	require.NoError(t, mp.Add(tx2, &FeerStub{}))
+	require.Equal(t, 2, len(mp.verifiedTxes))
+	require.Equal(t, 1, len(mp.fees))
+	require.Equal(t, utilityBalanceAndFees{
+		balance: util.Fixed8FromInt64(10000),
+		feeSum:  util.Fixed8FromInt64(10000),
+	}, mp.fees[sender0])
+
+	// can't add more transactions as we don't have enough GAS
+	tx3 := transaction.NewContractTX()
+	tx3.NetworkFee = util.Fixed8FromFloat(0.5)
+	tx3.Sender = sender0
+	require.Equal(t, false, mp.Verify(tx3, &FeerStub{}))
+	require.Error(t, mp.Add(tx3, &FeerStub{}))
+	require.Equal(t, 1, len(mp.fees))
+	require.Equal(t, utilityBalanceAndFees{
+		balance: util.Fixed8FromInt64(10000),
+		feeSum:  util.Fixed8FromInt64(10000),
+	}, mp.fees[sender0])
+
+	// check whether sender's fee updates correctly
+	mp.RemoveStale(func(t *transaction.Transaction) bool {
+		if t == tx2 {
+			return true
+		}
+		return false
+	}, &FeerStub{})
+	require.Equal(t, 1, len(mp.fees))
+	require.Equal(t, utilityBalanceAndFees{
+		balance: util.Fixed8FromInt64(10000),
+		feeSum:  util.Fixed8FromFloat(3000),
+	}, mp.fees[sender0])
+
+	// there should be nothing left
+	mp.RemoveStale(func(t *transaction.Transaction) bool {
+		if t == tx3 {
+			return true
+		}
+		return false
+	}, &FeerStub{})
+	require.Equal(t, 0, len(mp.fees))
+}
diff --git a/pkg/network/helper_test.go b/pkg/network/helper_test.go
index db2452eda..411afc88d 100644
--- a/pkg/network/helper_test.go
+++ b/pkg/network/helper_test.go
@@ -137,6 +137,10 @@ func (chain testChain) IsLowPriority(util.Fixed8) bool {
 	panic("TODO")
 }
 
+func (chain testChain) GetUtilityTokenBalance(uint160 util.Uint160) util.Fixed8 {
+	panic("TODO")
+}
+
 func (chain testChain) PoolTx(*transaction.Transaction) error {
 	panic("TODO")
 }
diff --git a/pkg/rpc/server/server_helper_test.go b/pkg/rpc/server/server_helper_test.go
index d8a0baa3d..b65897ab3 100644
--- a/pkg/rpc/server/server_helper_test.go
+++ b/pkg/rpc/server/server_helper_test.go
@@ -71,3 +71,7 @@ func (fs *FeerStub) IsLowPriority(util.Fixed8) bool {
 func (fs *FeerStub) FeePerByte() util.Fixed8 {
 	return 0
 }
+
+func (fs *FeerStub) GetUtilityTokenBalance(acc util.Uint160) util.Fixed8 {
+	return util.Fixed8FromInt64(1000000)
+}