diff --git a/x/auth/ante/ante_test.go b/x/auth/ante/ante_test.go
index b3d22061b668..60fe2149cd62 100644
--- a/x/auth/ante/ante_test.go
+++ b/x/auth/ante/ante_test.go
@@ -35,6 +35,58 @@ func checkInvalidTx(t *testing.T, anteHandler sdk.AnteHandler, ctx sdk.Context,
 	require.Equal(t, sdk.CodespaceRoot, result.Codespace)
 }
 
+// Test that simulate transaction accurately estimates gas cost
+func TestSimulateGasCost(t *testing.T) {
+	// setup
+	app, ctx := createTestApp(true)
+	ctx = ctx.WithBlockHeight(1)
+	anteHandler := ante.NewAnteHandler(app.AccountKeeper, app.SupplyKeeper, ante.DefaultSigVerificationGasConsumer)
+
+	// keys and addresses
+	priv1, _, addr1 := types.KeyTestPubAddr()
+	priv2, _, addr2 := types.KeyTestPubAddr()
+	priv3, _, addr3 := types.KeyTestPubAddr()
+
+	// set the accounts
+	acc1 := app.AccountKeeper.NewAccountWithAddress(ctx, addr1)
+	acc1.SetCoins(types.NewTestCoins())
+	require.NoError(t, acc1.SetAccountNumber(0))
+	app.AccountKeeper.SetAccount(ctx, acc1)
+	acc2 := app.AccountKeeper.NewAccountWithAddress(ctx, addr2)
+	acc2.SetCoins(types.NewTestCoins())
+	require.NoError(t, acc2.SetAccountNumber(1))
+	app.AccountKeeper.SetAccount(ctx, acc2)
+	acc3 := app.AccountKeeper.NewAccountWithAddress(ctx, addr3)
+	acc3.SetCoins(types.NewTestCoins())
+	require.NoError(t, acc3.SetAccountNumber(2))
+	app.AccountKeeper.SetAccount(ctx, acc3)
+
+	// set up msgs and fee
+	var tx sdk.Tx
+	msg1 := types.NewTestMsg(addr1, addr2)
+	msg2 := types.NewTestMsg(addr3, addr1)
+	msg3 := types.NewTestMsg(addr2, addr3)
+	msgs := []sdk.Msg{msg1, msg2, msg3}
+	fee := types.NewTestStdFee()
+
+	// signers in order. accnums are all 0 because it is in genesis block
+	privs, accnums, seqs := []crypto.PrivKey{priv1, priv2, priv3}, []uint64{0, 1, 2}, []uint64{0, 0, 0}
+	tx = types.NewTestTx(ctx, msgs, privs, accnums, seqs, fee)
+
+	cc, _ := ctx.CacheContext()
+	newCtx, err := anteHandler(cc, tx, true)
+	require.Nil(t, err, "transaction failed on simulate mode")
+
+	simulatedGas := newCtx.GasMeter().GasConsumed()
+	fee.Gas = simulatedGas
+
+	// update tx with simulated gas estimate
+	tx = types.NewTestTx(ctx, msgs, privs, accnums, seqs, fee)
+	_, err = anteHandler(ctx, tx, false)
+
+	require.Nil(t, err, "transaction failed with gas estimate")
+}
+
 // Test various error cases in the AnteHandler control flow.
 func TestAnteHandlerSigErrors(t *testing.T) {
 	// setup
diff --git a/x/auth/ante/fee.go b/x/auth/ante/fee.go
index d428cb713593..3d81808b2d0c 100644
--- a/x/auth/ante/fee.go
+++ b/x/auth/ante/fee.go
@@ -97,6 +97,10 @@ func (dfd DeductFeeDecorator) AnteHandle(ctx sdk.Context, tx sdk.Tx, simulate bo
 	feePayer := feeTx.FeePayer()
 	feePayerAcc := dfd.ak.GetAccount(ctx, feePayer)
 
+	if feePayerAcc == nil {
+		return ctx, sdkerrors.Wrapf(sdkerrors.ErrUnknownAddress, "fee payer address: %s does not exist", feePayer)
+	}
+
 	// deduct the fees
 	if !feeTx.GetFee().IsZero() {
 		err = DeductFees(dfd.supplyKeeper, ctx, feePayerAcc, feeTx.GetFee())
diff --git a/x/auth/ante/sigverify.go b/x/auth/ante/sigverify.go
index 4b340907e1e8..347015232100 100644
--- a/x/auth/ante/sigverify.go
+++ b/x/auth/ante/sigverify.go
@@ -59,9 +59,6 @@ func NewSetPubKeyDecorator(ak keeper.AccountKeeper) SetPubKeyDecorator {
 }
 
 func (spkd SetPubKeyDecorator) AnteHandle(ctx sdk.Context, tx sdk.Tx, simulate bool, next sdk.AnteHandler) (sdk.Context, error) {
-	if simulate {
-		return next(ctx, tx, simulate)
-	}
 	sigTx, ok := tx.(SigVerifiableTx)
 	if !ok {
 		return ctx, sdkerrors.Wrap(sdkerrors.ErrTxDecode, "invalid tx type")
@@ -73,9 +70,13 @@ func (spkd SetPubKeyDecorator) AnteHandle(ctx sdk.Context, tx sdk.Tx, simulate b
 	for i, pk := range pubkeys {
 		// PublicKey was omitted from slice since it has already been set in context
 		if pk == nil {
-			continue
+			if !simulate {
+				continue
+			}
+			pk = simSecp256k1Pubkey
 		}
-		if !bytes.Equal(pk.Address(), signers[i]) {
+		// Only make check if simulate=false
+		if !simulate && !bytes.Equal(pk.Address(), signers[i]) {
 			return ctx, sdkerrors.Wrapf(sdkerrors.ErrInvalidPubKey,
 				"pubKey does not match signer address %s with signer index: %d", signers[i], i)
 		}
@@ -84,6 +85,10 @@ func (spkd SetPubKeyDecorator) AnteHandle(ctx sdk.Context, tx sdk.Tx, simulate b
 		if err != nil {
 			return ctx, err
 		}
+		// account already has pubkey set,no need to reset
+		if acc.GetPubKey() != nil {
+			continue
+		}
 		err = acc.SetPubKey(pk)
 		if err != nil {
 			return ctx, sdkerrors.Wrap(sdkerrors.ErrInvalidPubKey, err.Error())
@@ -131,16 +136,22 @@ func (sgcd SigGasConsumeDecorator) AnteHandle(ctx sdk.Context, tx sdk.Tx, simula
 		pubKey := signerAcc.GetPubKey()
 
 		if simulate {
+			// In simulate mode the transaction comes with no signatures, thus if the
+			// account's pubkey is nil, both signature verification and gasKVStore.Set()
+			// shall consume the largest amount, i.e. it takes more gas to verify
+			// secp256k1 keys than ed25519 ones.
+			if pubKey == nil {
+				pubKey = simSecp256k1Pubkey
+			}
 			// Simulated txs should not contain a signature and are not required to
 			// contain a pubkey, so we must account for tx size of including a
 			// StdSignature (Amino encoding) and simulate gas consumption
 			// (assuming a SECP256k1 simulation key).
 			consumeSimSigGas(ctx.GasMeter(), pubKey, sig, params)
-		} else {
-			err = sgcd.sigGasConsumer(ctx.GasMeter(), sig, pubKey, params)
-			if err != nil {
-				return ctx, err
-			}
+		}
+		err = sgcd.sigGasConsumer(ctx.GasMeter(), sig, pubKey, params)
+		if err != nil {
+			return ctx, err
 		}
 	}