diff --git a/services/horizon/internal/txsub/system.go b/services/horizon/internal/txsub/system.go
index 2e61eeafc7..8712e5e418 100644
--- a/services/horizon/internal/txsub/system.go
+++ b/services/horizon/internal/txsub/system.go
@@ -147,6 +147,11 @@ func (sys *System) Submit(
 			return
 		}
 
+		if err = sys.waitUntilAccountSequence(ctx, db, sourceAddress, uint64(envelope.SeqNum())); err != nil {
+			sys.finish(ctx, hash, resultCh, Result{Err: err})
+			return
+		}
+
 		// If error is txBAD_SEQ, check for the result again
 		tx, err = txResultByHash(ctx, db, hash)
 		if err != nil {
@@ -164,6 +169,48 @@ func (sys *System) Submit(
 	return
 }
 
+// waitUntilAccountSequence blocks until either the context times out or the sequence number of the
+// given source account is greater than or equal to `seq`
+func (sys *System) waitUntilAccountSequence(ctx context.Context, db HorizonDB, sourceAddress string, seq uint64) error {
+	timer := time.NewTimer(sys.accountSeqPollInterval)
+	defer timer.Stop()
+
+	for {
+		sequenceNumbers, err := db.GetSequenceNumbers(ctx, []string{sourceAddress})
+		if err != nil {
+			sys.Log.Ctx(ctx).
+				WithError(err).
+				WithField("sourceAddress", sourceAddress).
+				Warn("cannot fetch sequence number")
+		} else {
+			num, ok := sequenceNumbers[sourceAddress]
+			if !ok {
+				sys.Log.Ctx(ctx).
+					WithField("sequenceNumbers", sequenceNumbers).
+					WithField("sourceAddress", sourceAddress).
+					Warn("missing sequence number for account")
+			}
+			if num >= seq {
+				return nil
+			}
+		}
+
+		select {
+		case <-ctx.Done():
+			return sys.deriveTxSubError(ctx)
+		case <-timer.C:
+			timer.Reset(sys.accountSeqPollInterval)
+		}
+	}
+}
+
+func (sys *System) deriveTxSubError(ctx context.Context) error {
+	if ctx.Err() == context.Canceled {
+		return ErrCanceled
+	}
+	return ErrTimeout
+}
+
 // Submit submits the provided base64 encoded transaction envelope to the
 // network using this submission system.
 func (sys *System) submitOnce(ctx context.Context, env string) SubmissionResult {
diff --git a/services/horizon/internal/txsub/system_test.go b/services/horizon/internal/txsub/system_test.go
index 02c8f2c063..e6bffc5987 100644
--- a/services/horizon/internal/txsub/system_test.go
+++ b/services/horizon/internal/txsub/system_test.go
@@ -146,6 +146,73 @@ func (suite *SystemTestSuite) TestSubmit_Basic() {
 	assert.False(suite.T(), suite.submitter.WasSubmittedTo)
 }
 
+func (suite *SystemTestSuite) TestTimeoutDuringSequnceLoop() {
+	var cancel context.CancelFunc
+	suite.ctx, cancel = context.WithTimeout(suite.ctx, time.Duration(0))
+	defer cancel()
+
+	suite.submitter.R = suite.badSeq
+	suite.db.On("BeginTx", mock.AnythingOfType("*context.timerCtx"), &sql.TxOptions{
+		Isolation: sql.LevelRepeatableRead,
+		ReadOnly:  true,
+	}).Return(nil).Once()
+	suite.db.On("Rollback").Return(nil).Once()
+	suite.db.On("PreFilteredTransactionByHash", suite.ctx, mock.Anything, suite.successTx.Transaction.TransactionHash).
+		Return(sql.ErrNoRows).Once()
+	suite.db.On("TransactionByHash", suite.ctx, mock.Anything, suite.successTx.Transaction.TransactionHash).
+		Return(sql.ErrNoRows).Once()
+	suite.db.On("NoRows", sql.ErrNoRows).Return(true).Twice()
+	suite.db.On("GetSequenceNumbers", suite.ctx, []string{suite.unmuxedSource.Address()}).
+		Return(map[string]uint64{suite.unmuxedSource.Address(): 0}, nil)
+
+	r := <-suite.system.Submit(
+		suite.ctx,
+		suite.successTx.Transaction.TxEnvelope,
+		suite.successXDR,
+		suite.successTx.Transaction.TransactionHash,
+	)
+
+	assert.NotNil(suite.T(), r.Err)
+	assert.Equal(suite.T(), ErrTimeout, r.Err)
+}
+
+func (suite *SystemTestSuite) TestClientDisconnectedDuringSequnceLoop() {
+	var cancel context.CancelFunc
+	suite.ctx, cancel = context.WithCancel(suite.ctx)
+
+	suite.submitter.R = suite.badSeq
+	suite.db.On("BeginTx", mock.AnythingOfType("*context.cancelCtx"), &sql.TxOptions{
+		Isolation: sql.LevelRepeatableRead,
+		ReadOnly:  true,
+	}).Return(nil).Once()
+	suite.db.On("Rollback").Return(nil).Once()
+	suite.db.On("PreFilteredTransactionByHash", suite.ctx, mock.Anything, suite.successTx.Transaction.TransactionHash).
+		Return(sql.ErrNoRows).Once()
+	suite.db.On("TransactionByHash", suite.ctx, mock.Anything, suite.successTx.Transaction.TransactionHash).
+		Return(sql.ErrNoRows).Once()
+	suite.db.On("NoRows", sql.ErrNoRows).Return(true).Twice()
+	suite.db.On("GetSequenceNumbers", suite.ctx, []string{suite.unmuxedSource.Address()}).
+		Return(map[string]uint64{suite.unmuxedSource.Address(): 0}, nil).
+		Run(func(args mock.Arguments) {
+			// simulate client disconnecting while looping on sequnce number check
+			cancel()
+			suite.ctx.Deadline()
+		}).
+		Once()
+	suite.db.On("GetSequenceNumbers", suite.ctx, []string{suite.unmuxedSource.Address()}).
+		Return(map[string]uint64{suite.unmuxedSource.Address(): 0}, nil)
+
+	r := <-suite.system.Submit(
+		suite.ctx,
+		suite.successTx.Transaction.TxEnvelope,
+		suite.successXDR,
+		suite.successTx.Transaction.TransactionHash,
+	)
+
+	assert.NotNil(suite.T(), r.Err)
+	assert.Equal(suite.T(), ErrCanceled, r.Err)
+}
+
 func getMetricValue(metric prometheus.Metric) *dto.Metric {
 	value := &dto.Metric{}
 	err := metric.Write(value)
@@ -198,6 +265,9 @@ func (suite *SystemTestSuite) TestSubmit_BadSeq() {
 	suite.db.On("GetSequenceNumbers", suite.ctx, []string{suite.unmuxedSource.Address()}).
 		Return(map[string]uint64{suite.unmuxedSource.Address(): 0}, nil).
 		Once()
+	suite.db.On("GetSequenceNumbers", suite.ctx, []string{suite.unmuxedSource.Address()}).
+		Return(map[string]uint64{suite.unmuxedSource.Address(): 1}, nil).
+		Once()
 	suite.db.On("PreFilteredTransactionByHash", suite.ctx, mock.Anything, suite.successTx.Transaction.TransactionHash).
 		Return(sql.ErrNoRows).Twice()
 	suite.db.On("NoRows", sql.ErrNoRows).Return(true).Once()
@@ -239,6 +309,9 @@ func (suite *SystemTestSuite) TestSubmit_BadSeqNotFound() {
 	suite.db.On("NoRows", sql.ErrNoRows).Return(true).Twice()
 	suite.db.On("GetSequenceNumbers", suite.ctx, []string{suite.unmuxedSource.Address()}).
 		Return(map[string]uint64{suite.unmuxedSource.Address(): 0}, nil).
+		Times(3)
+	suite.db.On("GetSequenceNumbers", suite.ctx, []string{suite.unmuxedSource.Address()}).
+		Return(map[string]uint64{suite.unmuxedSource.Address(): 1}, nil).
 		Once()
 
 	// set poll interval to 1ms so we don't need to wait 3 seconds for the test to complete