diff --git a/package-lock.json b/package-lock.json
index 7832235..56a04fa 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -2104,7 +2104,7 @@
     },
     "node_modules/@rsksmart/rif-relay-client": {
       "version": "2.2.1",
-      "resolved": "git+ssh://git@github.com/rsksmart/rif-relay-client.git#cf173b8372afea5a400fbdcfc1ffb0c66c99ca8f",
+      "resolved": "git+ssh://git@github.com/rsksmart/rif-relay-client.git#e634dc7b14ebd130538738257a7dec326000feca",
       "license": "MIT",
       "dependencies": {
         "bignumber.js": "^9.1.1",
@@ -13447,7 +13447,7 @@
       "integrity": "sha512-z0zMCjyhhp4y7XKAcDAi3Vgms4T2PstwBdahiO0+9NaGICQKjynK3wduSRplTgk4LXmoO1yfDGO5RbjKYxtuxA=="
     },
     "@rsksmart/rif-relay-client": {
-      "version": "git+ssh://git@github.com/rsksmart/rif-relay-client.git#cf173b8372afea5a400fbdcfc1ffb0c66c99ca8f",
+      "version": "git+ssh://git@github.com/rsksmart/rif-relay-client.git#e634dc7b14ebd130538738257a7dec326000feca",
       "from": "@rsksmart/rif-relay-client@github:rsksmart/rif-relay-client#fix/payment-gas-estimation",
       "requires": {
         "bignumber.js": "^9.1.1",
diff --git a/src/RelayServer.ts b/src/RelayServer.ts
index 5c28453..520a8b0 100644
--- a/src/RelayServer.ts
+++ b/src/RelayServer.ts
@@ -447,16 +447,26 @@ export class RelayServer extends EventEmitter {
       `EnvelopingRequest:${JSON.stringify(envelopingRequest, undefined, 4)}`
     );
 
+    this.validateInputTypes(envelopingRequest);
+
+    const {
+      relayRequest,
+      metadata: { isCustom },
+    } = envelopingRequest;
+
     const initialGasEstimation = await estimateRelayMaxPossibleGas(
       envelopingRequest,
-      this.workerAddress
+      this.workerAddress,
+      {
+        isCustom,
+      }
     );
     log.debug(
       `Gas estimation before fees:  ${initialGasEstimation.toString()}`
     );
 
     const fee = await calculateFee(
-      envelopingRequest.relayRequest,
+      relayRequest,
       initialGasEstimation,
       this.config.app
     );
@@ -472,7 +482,7 @@ export class RelayServer extends EventEmitter {
     );
 
     const conversionResult = await convertGasToTokenAndNative(
-      envelopingRequest.relayRequest,
+      relayRequest,
       maxPossibleGas
     );
     log.debug(
diff --git a/src/Utils.ts b/src/Utils.ts
index efbd28d..ca8acf8 100644
--- a/src/Utils.ts
+++ b/src/Utils.ts
@@ -148,6 +148,7 @@ export const deployTransactionRequestShape = {
     relayHubAddress: ow.string,
     relayMaxNonce: ow.number,
     signature: ow.string,
+    isCustom: ow.optional.boolean,
   },
 };
 
@@ -178,5 +179,6 @@ export const relayTransactionRequestShape = {
     relayHubAddress: ow.string,
     relayMaxNonce: ow.number,
     signature: ow.string,
+    isCustom: ow.optional.boolean,
   },
 };
diff --git a/src/definitions/httpEnvelopingRequest.type.ts b/src/definitions/httpEnvelopingRequest.type.ts
index 9004ace..771750e 100644
--- a/src/definitions/httpEnvelopingRequest.type.ts
+++ b/src/definitions/httpEnvelopingRequest.type.ts
@@ -18,6 +18,7 @@ export declare type EnvelopingMetadata = {
   relayHubAddress: RelayRequestBody['relayHub'];
   relayMaxNonce: number;
   signature: string;
+  isCustom?: boolean;
 };
 
 export declare type EnvelopingRequestData = {
diff --git a/test/unit/RelayServer.test.ts b/test/unit/RelayServer.test.ts
index 3f7a2f7..4afcabb 100644
--- a/test/unit/RelayServer.test.ts
+++ b/test/unit/RelayServer.test.ts
@@ -209,6 +209,7 @@ describe('RelayServer tests', function () {
   describe('Function estimateMaxPossibleGas()', function () {
     it('should return only the initial estimation when there are no additional fees', async function () {
       sinon.stub(relayServerUtils, 'calculateFee').resolves(BigNumberJs(0));
+      sinon.stub(relayServer, 'validateInputTypes').returns();
 
       const maxPossibleGasEstimation = await relayServer.estimateMaxPossibleGas(
         {
@@ -220,6 +221,7 @@ describe('RelayServer tests', function () {
               gasPrice: GAS_PRICE,
             },
           },
+          metadata: {},
         } as HttpEnvelopingRequest
       );
 
@@ -232,6 +234,7 @@ describe('RelayServer tests', function () {
       sinon
         .stub(relayServerUtils, 'calculateFee')
         .resolves(BigNumberJs(FAKE_FEE_AMOUNT));
+      sinon.stub(relayServer, 'validateInputTypes').returns();
 
       const maxPossibleGasEstimation = await relayServer.estimateMaxPossibleGas(
         {
@@ -243,6 +246,7 @@ describe('RelayServer tests', function () {
               gasPrice: GAS_PRICE,
             },
           },
+          metadata: {},
         } as HttpEnvelopingRequest
       );
 
@@ -311,6 +315,8 @@ describe('RelayServer tests', function () {
         .stub(relayServerUtils, 'calculateFee')
         .resolves(BigNumberJs(FAKE_FEE_AMOUNT));
 
+      sinon.stub(relayServer, 'validateInputTypes').returns();
+
       const estimatedGas = await relayServer.estimateMaxPossibleGas({
         relayRequest: {
           request: {
@@ -320,6 +326,7 @@ describe('RelayServer tests', function () {
             gasPrice: GAS_PRICE,
           },
         },
+        metadata: {},
       } as HttpEnvelopingRequest);
 
       const { maxPossibleGasWithFee } = await relayServer.getMaxPossibleGas({
@@ -331,6 +338,7 @@ describe('RelayServer tests', function () {
             gasPrice: GAS_PRICE,
           },
         },
+        metadata: {},
       } as HttpEnvelopingRequest);
 
       expect(estimatedGas.estimation.toString()).to.be.eq(