diff --git a/.changeset/unlucky-tips-smash.md b/.changeset/unlucky-tips-smash.md
new file mode 100644
index 0000000..532c35a
--- /dev/null
+++ b/.changeset/unlucky-tips-smash.md
@@ -0,0 +1,5 @@
+---
+"saleor-app-taxes": patch
+---
+
+Fixed the error when checkout couldn't calculate taxes when no customerCode was provided. In calculate taxes, the customerCode is now derived from issuingPrincipal's id.
diff --git a/apps/taxes/graphql/fragments/CalculateTaxesEvent.graphql b/apps/taxes/graphql/fragments/CalculateTaxesEvent.graphql
index 08c11e0..0273ede 100644
--- a/apps/taxes/graphql/fragments/CalculateTaxesEvent.graphql
+++ b/apps/taxes/graphql/fragments/CalculateTaxesEvent.graphql
@@ -10,5 +10,11 @@ fragment CalculateTaxesEvent on Event {
         value
       }
     }
+    issuingPrincipal {
+      __typename
+      ... on User {
+        id
+      }
+    }
   }
 }
diff --git a/apps/taxes/graphql/fragments/TaxBase.graphql b/apps/taxes/graphql/fragments/TaxBase.graphql
index 2c28eb7..0a0efbf 100644
--- a/apps/taxes/graphql/fragments/TaxBase.graphql
+++ b/apps/taxes/graphql/fragments/TaxBase.graphql
@@ -62,15 +62,9 @@ fragment TaxBase on TaxableObject {
   sourceObject {
     ... on Checkout {
       avataxEntityCode: metafield(key: "avataxEntityCode")
-      user {
-        id
-      }
     }
     ... on Order {
       avataxEntityCode: metafield(key: "avataxEntityCode")
-      user {
-        id
-      }
     }
   }
 }
diff --git a/apps/taxes/src/modules/avatax/avatax-webhook.service.ts b/apps/taxes/src/modules/avatax/avatax-webhook.service.ts
index c53f768..95a46aa 100644
--- a/apps/taxes/src/modules/avatax/avatax-webhook.service.ts
+++ b/apps/taxes/src/modules/avatax/avatax-webhook.service.ts
@@ -8,6 +8,7 @@ import { AvataxConfig, defaultAvataxConfig } from "./avatax-connection-schema";
 import { AvataxCalculateTaxesAdapter } from "./calculate-taxes/avatax-calculate-taxes-adapter";
 import { AvataxOrderCancelledAdapter } from "./order-cancelled/avatax-order-cancelled-adapter";
 import { AvataxOrderConfirmedAdapter } from "./order-confirmed/avatax-order-confirmed-adapter";
+import { CalculateTaxesPayload } from "../../pages/api/webhooks/checkout-calculate-taxes";
 
 export class AvataxWebhookService implements ProviderWebhookService {
   config = defaultAvataxConfig;
@@ -27,10 +28,10 @@ export class AvataxWebhookService implements ProviderWebhookService {
     this.client = avataxClient;
   }
 
-  async calculateTaxes(taxBase: TaxBaseFragment) {
+  async calculateTaxes(payload: CalculateTaxesPayload) {
     const adapter = new AvataxCalculateTaxesAdapter(this.config, this.authData);
 
-    const response = await adapter.send({ taxBase });
+    const response = await adapter.send(payload);
 
     return response;
   }
diff --git a/apps/taxes/src/modules/avatax/calculate-taxes/avatax-calculate-taxes-adapter.ts b/apps/taxes/src/modules/avatax/calculate-taxes/avatax-calculate-taxes-adapter.ts
index 02d7a3e..5435a31 100644
--- a/apps/taxes/src/modules/avatax/calculate-taxes/avatax-calculate-taxes-adapter.ts
+++ b/apps/taxes/src/modules/avatax/calculate-taxes/avatax-calculate-taxes-adapter.ts
@@ -1,6 +1,6 @@
 import { AuthData } from "@saleor/app-sdk/APL";
-import { TaxBaseFragment } from "../../../../generated/graphql";
 import { Logger, createLogger } from "../../../lib/logger";
+import { CalculateTaxesPayload } from "../../../pages/api/webhooks/checkout-calculate-taxes";
 import { CalculateTaxesResponse } from "../../taxes/tax-provider-webhook";
 import { WebhookAdapter } from "../../taxes/tax-webhook-adapter";
 import { AvataxClient, CreateTransactionArgs } from "../avatax-client";
@@ -10,26 +10,27 @@ import { AvataxCalculateTaxesResponseTransformer } from "./avatax-calculate-taxe
 
 export const SHIPPING_ITEM_CODE = "Shipping";
 
-export type AvataxCalculateTaxesPayload = {
-  taxBase: TaxBaseFragment;
-};
-
 export type AvataxCalculateTaxesTarget = CreateTransactionArgs;
 export type AvataxCalculateTaxesResponse = CalculateTaxesResponse;
 
 export class AvataxCalculateTaxesAdapter
-  implements WebhookAdapter<AvataxCalculateTaxesPayload, AvataxCalculateTaxesResponse>
+  implements WebhookAdapter<CalculateTaxesPayload, AvataxCalculateTaxesResponse>
 {
   private logger: Logger;
-  constructor(private readonly config: AvataxConfig, private authData: AuthData) {
+  constructor(
+    private readonly config: AvataxConfig,
+    private authData: AuthData,
+  ) {
     this.logger = createLogger({ name: "AvataxCalculateTaxesAdapter" });
   }
 
-  // todo: refactor because its getting too big
-  async send(payload: AvataxCalculateTaxesPayload): Promise<AvataxCalculateTaxesResponse> {
-    this.logger.debug("Transforming the Saleor payload for calculating taxes with AvaTax...");
+  async send(payload: CalculateTaxesPayload): Promise<AvataxCalculateTaxesResponse> {
+    this.logger.debug(
+      { payload },
+      "Transforming the Saleor payload for calculating taxes with AvaTax...",
+    );
     const payloadService = new AvataxCalculateTaxesPayloadService(this.authData);
-    const target = await payloadService.getPayload(payload.taxBase, this.config);
+    const target = await payloadService.getPayload(payload, this.config);
 
     this.logger.debug("Calling AvaTax createTransaction with transformed payload...");
 
diff --git a/apps/taxes/src/modules/avatax/calculate-taxes/avatax-calculate-taxes-mock-generator.ts b/apps/taxes/src/modules/avatax/calculate-taxes/avatax-calculate-taxes-mock-generator.ts
index 4e7797a..67955a4 100644
--- a/apps/taxes/src/modules/avatax/calculate-taxes/avatax-calculate-taxes-mock-generator.ts
+++ b/apps/taxes/src/modules/avatax/calculate-taxes/avatax-calculate-taxes-mock-generator.ts
@@ -107,9 +107,6 @@ const defaultTaxBase: TaxBase = {
   ],
   sourceObject: {
     avataxEntityCode: null,
-    user: {
-      id: "VXNlcjoyMDg0NTEwNDEw",
-    },
   },
 };
 
diff --git a/apps/taxes/src/modules/avatax/calculate-taxes/avatax-calculate-taxes-payload-transformer.test.ts b/apps/taxes/src/modules/avatax/calculate-taxes/avatax-calculate-taxes-payload-transformer.test.ts
index de4729f..1612af1 100644
--- a/apps/taxes/src/modules/avatax/calculate-taxes/avatax-calculate-taxes-payload-transformer.test.ts
+++ b/apps/taxes/src/modules/avatax/calculate-taxes/avatax-calculate-taxes-payload-transformer.test.ts
@@ -2,6 +2,7 @@ import { describe, expect, it } from "vitest";
 import { AvataxCalculateTaxesMockGenerator } from "./avatax-calculate-taxes-mock-generator";
 import { AvataxCalculateTaxesPayloadTransformer } from "./avatax-calculate-taxes-payload-transformer";
 import { DocumentType } from "avatax/lib/enums/DocumentType";
+import { CalculateTaxesPayload } from "../../../pages/api/webhooks/checkout-calculate-taxes";
 
 const mockGenerator = new AvataxCalculateTaxesMockGenerator();
 const avataxConfigMock = mockGenerator.generateAvataxConfig();
@@ -10,11 +11,18 @@ describe("AvataxCalculateTaxesPayloadTransformer", () => {
   it("returns document type of SalesInvoice", async () => {
     const taxBaseMock = mockGenerator.generateTaxBase();
     const matchesMock = mockGenerator.generateTaxCodeMatches();
+    const payloadMock = {
+      taxBase: taxBaseMock,
+      issuingPrincipal: {
+        __typename: "User",
+        id: "1",
+      },
+    } as unknown as CalculateTaxesPayload;
 
     const payload = await new AvataxCalculateTaxesPayloadTransformer().transform(
-      taxBaseMock,
+      payloadMock,
       avataxConfigMock,
-      matchesMock
+      matchesMock,
     );
 
     expect(payload.model.type).toBe(DocumentType.SalesOrder);
@@ -22,27 +30,56 @@ describe("AvataxCalculateTaxesPayloadTransformer", () => {
   it("when discounts, calculates the sum of discounts", async () => {
     const taxBaseMock = mockGenerator.generateTaxBase({ discounts: [{ amount: { amount: 10 } }] });
     const matchesMock = mockGenerator.generateTaxCodeMatches();
+    const payloadMock = {
+      taxBase: taxBaseMock,
+      issuingPrincipal: {
+        __typename: "User",
+        id: "1",
+      },
+    } as unknown as CalculateTaxesPayload;
 
     const payload = await new AvataxCalculateTaxesPayloadTransformer().transform(
-      taxBaseMock,
+      payloadMock,
       avataxConfigMock,
-      matchesMock
+      matchesMock,
     );
 
     expect(payload.model.discount).toEqual(10);
   });
   it("when no discounts, the sum of discount is 0", async () => {
-    const mockGenerator = new AvataxCalculateTaxesMockGenerator();
-    const avataxConfigMock = mockGenerator.generateAvataxConfig();
     const taxBaseMock = mockGenerator.generateTaxBase();
     const matchesMock = mockGenerator.generateTaxCodeMatches();
 
+    const payloadMock = {
+      taxBase: taxBaseMock,
+      issuingPrincipal: {
+        __typename: "User",
+        id: "1",
+      },
+    } as unknown as CalculateTaxesPayload;
+
     const payload = await new AvataxCalculateTaxesPayloadTransformer().transform(
-      taxBaseMock,
+      payloadMock,
       avataxConfigMock,
-      matchesMock
+      matchesMock,
     );
 
     expect(payload.model.discount).toEqual(0);
   });
+  it("when no issuingPrincipal.id, throws an error", async () => {
+    const taxBaseMock = mockGenerator.generateTaxBase();
+    const matchesMock = mockGenerator.generateTaxCodeMatches();
+
+    const payloadMock = {
+      taxBase: taxBaseMock,
+    } as unknown as CalculateTaxesPayload;
+
+    await expect(
+      new AvataxCalculateTaxesPayloadTransformer().transform(
+        payloadMock,
+        avataxConfigMock,
+        matchesMock,
+      ),
+    ).rejects.toThrow("This field must be defined.");
+  });
 });
diff --git a/apps/taxes/src/modules/avatax/calculate-taxes/avatax-calculate-taxes-payload-transformer.ts b/apps/taxes/src/modules/avatax/calculate-taxes/avatax-calculate-taxes-payload-transformer.ts
index 97f4c9e..1eb5e99 100644
--- a/apps/taxes/src/modules/avatax/calculate-taxes/avatax-calculate-taxes-payload-transformer.ts
+++ b/apps/taxes/src/modules/avatax/calculate-taxes/avatax-calculate-taxes-payload-transformer.ts
@@ -7,6 +7,8 @@ import { AvataxConfig, defaultAvataxConfig } from "../avatax-connection-schema";
 import { AvataxTaxCodeMatches } from "../tax-code/avatax-tax-code-match-repository";
 import { AvataxCalculateTaxesPayloadLinesTransformer } from "./avatax-calculate-taxes-payload-lines-transformer";
 import { AvataxEntityTypeMatcher } from "../avatax-entity-type-matcher";
+import { taxProviderUtils } from "../../taxes/tax-provider-utils";
+import { CalculateTaxesPayload } from "../../../pages/api/webhooks/checkout-calculate-taxes";
 
 export class AvataxCalculateTaxesPayloadTransformer {
   private matchDocumentType(config: AvataxConfig): DocumentType {
@@ -20,32 +22,38 @@ export class AvataxCalculateTaxesPayloadTransformer {
   }
 
   async transform(
-    taxBase: TaxBaseFragment,
+    payload: CalculateTaxesPayload,
     avataxConfig: AvataxConfig,
-    matches: AvataxTaxCodeMatches
+    matches: AvataxTaxCodeMatches,
   ): Promise<CreateTransactionArgs> {
     const payloadLinesTransformer = new AvataxCalculateTaxesPayloadLinesTransformer();
     const avataxClient = new AvataxClient(avataxConfig);
     const entityTypeMatcher = new AvataxEntityTypeMatcher({ client: avataxClient });
-    const entityUseCode = await entityTypeMatcher.match(taxBase.sourceObject.avataxEntityCode);
+    const entityUseCode = await entityTypeMatcher.match(
+      payload.taxBase.sourceObject.avataxEntityCode,
+    );
+
+    const customerCode = taxProviderUtils.resolveStringOrThrow(
+      payload.issuingPrincipal?.__typename === "User" ? payload.issuingPrincipal.id : undefined,
+    );
 
     return {
       model: {
         type: this.matchDocumentType(avataxConfig),
         entityUseCode,
-        customerCode: taxBase.sourceObject.user?.id ?? "",
+        customerCode,
         companyCode: avataxConfig.companyCode ?? defaultAvataxConfig.companyCode,
         // * commit: If true, the transaction will be committed immediately after it is created. See: https://developer.avalara.com/communications/dev-guide_rest_v2/commit-uncommit
         commit: avataxConfig.isAutocommit,
         addresses: {
           shipFrom: avataxAddressFactory.fromChannelAddress(avataxConfig.address),
-          shipTo: avataxAddressFactory.fromSaleorAddress(taxBase.address!),
+          shipTo: avataxAddressFactory.fromSaleorAddress(payload.taxBase.address!),
         },
-        currencyCode: taxBase.currency,
-        lines: payloadLinesTransformer.transform(taxBase, avataxConfig, matches),
+        currencyCode: payload.taxBase.currency,
+        lines: payloadLinesTransformer.transform(payload.taxBase, avataxConfig, matches),
         date: new Date(),
         discount: discountUtils.sumDiscounts(
-          taxBase.discounts.map((discount) => discount.amount.amount)
+          payload.taxBase.discounts.map((discount) => discount.amount.amount),
         ),
       },
     };
diff --git a/apps/taxes/src/modules/avatax/calculate-taxes/avatax-calculate-taxes-payload.service.ts b/apps/taxes/src/modules/avatax/calculate-taxes/avatax-calculate-taxes-payload.service.ts
index 76a9fbe..e3dcc57 100644
--- a/apps/taxes/src/modules/avatax/calculate-taxes/avatax-calculate-taxes-payload.service.ts
+++ b/apps/taxes/src/modules/avatax/calculate-taxes/avatax-calculate-taxes-payload.service.ts
@@ -4,6 +4,7 @@ import { CreateTransactionArgs } from "../avatax-client";
 import { AvataxConfig } from "../avatax-connection-schema";
 import { AvataxTaxCodeMatchesService } from "../tax-code/avatax-tax-code-matches.service";
 import { AvataxCalculateTaxesPayloadTransformer } from "./avatax-calculate-taxes-payload-transformer";
+import { CalculateTaxesPayload } from "../../../pages/api/webhooks/checkout-calculate-taxes";
 
 export class AvataxCalculateTaxesPayloadService {
   constructor(private authData: AuthData) {}
@@ -15,12 +16,12 @@ export class AvataxCalculateTaxesPayloadService {
   }
 
   async getPayload(
-    taxBase: TaxBaseFragment,
-    avataxConfig: AvataxConfig
+    payload: CalculateTaxesPayload,
+    avataxConfig: AvataxConfig,
   ): Promise<CreateTransactionArgs> {
     const matches = await this.getMatches();
     const payloadTransformer = new AvataxCalculateTaxesPayloadTransformer();
 
-    return payloadTransformer.transform(taxBase, avataxConfig, matches);
+    return payloadTransformer.transform(payload, avataxConfig, matches);
   }
 }
diff --git a/apps/taxes/src/modules/avatax/order-confirmed/avatax-order-confirmed-payload-transformer.ts b/apps/taxes/src/modules/avatax/order-confirmed/avatax-order-confirmed-payload-transformer.ts
index a694257..469e9f8 100644
--- a/apps/taxes/src/modules/avatax/order-confirmed/avatax-order-confirmed-payload-transformer.ts
+++ b/apps/taxes/src/modules/avatax/order-confirmed/avatax-order-confirmed-payload-transformer.ts
@@ -25,7 +25,7 @@ export class AvataxOrderConfirmedPayloadTransformer {
   async transform(
     order: OrderConfirmedSubscriptionFragment,
     avataxConfig: AvataxConfig,
-    matches: AvataxTaxCodeMatches
+    matches: AvataxTaxCodeMatches,
   ): Promise<CreateTransactionArgs> {
     const avataxClient = new AvataxClient(avataxConfig);
 
@@ -46,9 +46,7 @@ export class AvataxOrderConfirmedPayloadTransformer {
         code,
         type: this.matchDocumentType(avataxConfig),
         entityUseCode,
-        customerCode:
-          order.user?.id ??
-          "" /* In Saleor AvaTax plugin, the customer code is 0. In Taxes App, we set it to the user id. */,
+        customerCode: taxProviderUtils.resolveStringOrThrow(order.user?.id),
         companyCode: avataxConfig.companyCode ?? defaultAvataxConfig.companyCode,
         // * commit: If true, the transaction will be committed immediately after it is created. See: https://developer.avalara.com/communications/dev-guide_rest_v2/commit-uncommit
         commit: avataxConfig.isAutocommit,
@@ -62,7 +60,7 @@ export class AvataxOrderConfirmedPayloadTransformer {
         lines: linesTransformer.transform(order, avataxConfig, matches),
         date,
         discount: discountUtils.sumDiscounts(
-          order.discounts.map((discount) => discount.amount.amount)
+          order.discounts.map((discount) => discount.amount.amount),
         ),
       },
     };
diff --git a/apps/taxes/src/modules/taxes/get-active-connection-service.ts b/apps/taxes/src/modules/taxes/get-active-connection-service.ts
index 24c4cd2..35fb7e5 100644
--- a/apps/taxes/src/modules/taxes/get-active-connection-service.ts
+++ b/apps/taxes/src/modules/taxes/get-active-connection-service.ts
@@ -12,6 +12,7 @@ import { AvataxWebhookService } from "../avatax/avatax-webhook.service";
 import { ProviderConnection } from "../provider-connections/provider-connections";
 import { TaxJarWebhookService } from "../taxjar/taxjar-webhook.service";
 import { ProviderWebhookService } from "./tax-provider-webhook";
+import { CalculateTaxesPayload } from "../../pages/api/webhooks/checkout-calculate-taxes";
 
 // todo: refactor to a factory
 class ActiveTaxProviderService implements ProviderWebhookService {
@@ -47,7 +48,7 @@ class ActiveTaxProviderService implements ProviderWebhookService {
     }
   }
 
-  async calculateTaxes(payload: TaxBaseFragment) {
+  async calculateTaxes(payload: CalculateTaxesPayload) {
     return this.client.calculateTaxes(payload);
   }
 
diff --git a/apps/taxes/src/modules/taxes/tax-provider-utils.ts b/apps/taxes/src/modules/taxes/tax-provider-utils.ts
index 31f81b6..5e12986 100644
--- a/apps/taxes/src/modules/taxes/tax-provider-utils.ts
+++ b/apps/taxes/src/modules/taxes/tax-provider-utils.ts
@@ -16,7 +16,10 @@ function resolveOptionalOrThrow<T>(value: T | undefined | null, error?: Error):
 }
 
 function resolveStringOrThrow(value: string | undefined | null): string {
-  return z.string().min(1, { message: "This field can not be empty." }).parse(value);
+  return z
+    .string({ required_error: "This field must be defined." })
+    .min(1, { message: "This field can not be empty." })
+    .parse(value);
 }
 
 export const taxProviderUtils = {
diff --git a/apps/taxes/src/modules/taxes/tax-provider-webhook.ts b/apps/taxes/src/modules/taxes/tax-provider-webhook.ts
index 78bbf69..9c08236 100644
--- a/apps/taxes/src/modules/taxes/tax-provider-webhook.ts
+++ b/apps/taxes/src/modules/taxes/tax-provider-webhook.ts
@@ -1,5 +1,6 @@
 import { SyncWebhookResponsesMap } from "@saleor/app-sdk/handlers/next";
-import { OrderConfirmedSubscriptionFragment, TaxBaseFragment } from "../../../generated/graphql";
+import { OrderConfirmedSubscriptionFragment } from "../../../generated/graphql";
+import { CalculateTaxesPayload } from "../../pages/api/webhooks/checkout-calculate-taxes";
 import { OrderCancelledPayload } from "../../pages/api/webhooks/order-cancelled";
 
 export type CalculateTaxesResponse = SyncWebhookResponsesMap["ORDER_CALCULATE_TAXES"];
@@ -7,7 +8,7 @@ export type CalculateTaxesResponse = SyncWebhookResponsesMap["ORDER_CALCULATE_TA
 export type CreateOrderResponse = { id: string };
 
 export interface ProviderWebhookService {
-  calculateTaxes: (payload: TaxBaseFragment) => Promise<CalculateTaxesResponse>;
+  calculateTaxes: (payload: CalculateTaxesPayload) => Promise<CalculateTaxesResponse>;
   confirmOrder: (payload: OrderConfirmedSubscriptionFragment) => Promise<CreateOrderResponse>;
   cancelOrder: (payload: OrderCancelledPayload) => Promise<void>;
 }
diff --git a/apps/taxes/src/modules/taxjar/calculate-taxes/taxjar-calculate-taxes-mock-generator.ts b/apps/taxes/src/modules/taxjar/calculate-taxes/taxjar-calculate-taxes-mock-generator.ts
index 352f50a..8d80ffd 100644
--- a/apps/taxes/src/modules/taxjar/calculate-taxes/taxjar-calculate-taxes-mock-generator.ts
+++ b/apps/taxes/src/modules/taxjar/calculate-taxes/taxjar-calculate-taxes-mock-generator.ts
@@ -96,9 +96,6 @@ const taxIncludedTaxBase: TaxBase = {
   ],
   sourceObject: {
     avataxEntityCode: null,
-    user: {
-      id: "VXNlcjoyMDg0NTEwNDEw",
-    },
   },
 };
 
@@ -194,9 +191,6 @@ const taxExcludedTaxBase: TaxBase = {
   ],
   sourceObject: {
     avataxEntityCode: null,
-    user: {
-      id: "VXNlcjoyMDg0NTEwNDEw",
-    },
   },
 };
 
diff --git a/apps/taxes/src/modules/taxjar/taxjar-webhook.service.ts b/apps/taxes/src/modules/taxjar/taxjar-webhook.service.ts
index e160a19..3a742bb 100644
--- a/apps/taxes/src/modules/taxjar/taxjar-webhook.service.ts
+++ b/apps/taxes/src/modules/taxjar/taxjar-webhook.service.ts
@@ -10,6 +10,7 @@ import { TaxJarCalculateTaxesAdapter } from "./calculate-taxes/taxjar-calculate-
 import { TaxJarOrderConfirmedAdapter } from "./order-confirmed/taxjar-order-confirmed-adapter";
 import { TaxJarClient } from "./taxjar-client";
 import { TaxJarConfig } from "./taxjar-connection-schema";
+import { CalculateTaxesPayload } from "../../pages/api/webhooks/checkout-calculate-taxes";
 
 export class TaxJarWebhookService implements ProviderWebhookService {
   client: TaxJarClient;
@@ -29,10 +30,10 @@ export class TaxJarWebhookService implements ProviderWebhookService {
     });
   }
 
-  async calculateTaxes(taxBase: TaxBaseFragment) {
+  async calculateTaxes(payload: CalculateTaxesPayload) {
     const adapter = new TaxJarCalculateTaxesAdapter(this.config, this.authData);
 
-    const response = await adapter.send({ taxBase });
+    const response = await adapter.send(payload);
 
     return response;
   }
diff --git a/apps/taxes/src/pages/api/webhooks/checkout-calculate-taxes.ts b/apps/taxes/src/pages/api/webhooks/checkout-calculate-taxes.ts
index af9bd3e..092b244 100644
--- a/apps/taxes/src/pages/api/webhooks/checkout-calculate-taxes.ts
+++ b/apps/taxes/src/pages/api/webhooks/checkout-calculate-taxes.ts
@@ -14,7 +14,10 @@ export const config = {
   },
 };
 
-type CalculateTaxesPayload = Extract<CalculateTaxesEventFragment, { __typename: "CalculateTaxes" }>;
+export type CalculateTaxesPayload = Extract<
+  CalculateTaxesEventFragment,
+  { __typename: "CalculateTaxes" }
+>;
 
 function verifyCalculateTaxesPayload(payload: CalculateTaxesPayload) {
   if (!payload.taxBase.lines) {
@@ -52,11 +55,11 @@ export default checkoutCalculateTaxesSyncWebhook.createHandler(async (req, res,
     const activeConnectionService = getActiveConnectionService(
       channelSlug,
       appMetadata,
-      ctx.authData
+      ctx.authData,
     );
 
     logger.info("Found active connection service. Calculating taxes...");
-    const calculatedTaxes = await activeConnectionService.calculateTaxes(payload.taxBase);
+    const calculatedTaxes = await activeConnectionService.calculateTaxes(payload);
 
     logger.info({ calculatedTaxes }, "Taxes calculated");
     return webhookResponse.success(ctx.buildResponse(calculatedTaxes));
diff --git a/apps/taxes/src/pages/api/webhooks/order-calculate-taxes.ts b/apps/taxes/src/pages/api/webhooks/order-calculate-taxes.ts
index e8ed2ed..9fe1348 100644
--- a/apps/taxes/src/pages/api/webhooks/order-calculate-taxes.ts
+++ b/apps/taxes/src/pages/api/webhooks/order-calculate-taxes.ts
@@ -52,11 +52,11 @@ export default orderCalculateTaxesSyncWebhook.createHandler(async (req, res, ctx
     const activeConnectionService = getActiveConnectionService(
       channelSlug,
       appMetadata,
-      ctx.authData
+      ctx.authData,
     );
 
     logger.info("Found active connection service. Calculating taxes...");
-    const calculatedTaxes = await activeConnectionService.calculateTaxes(payload.taxBase);
+    const calculatedTaxes = await activeConnectionService.calculateTaxes(payload);
 
     logger.info({ calculatedTaxes }, "Taxes calculated");
     return webhookResponse.success(ctx.buildResponse(calculatedTaxes));