diff --git a/packages/app/src/cli/models/app/loader.test.ts b/packages/app/src/cli/models/app/loader.test.ts
index d537b43e93..9a0e4ef87f 100644
--- a/packages/app/src/cli/models/app/loader.test.ts
+++ b/packages/app/src/cli/models/app/loader.test.ts
@@ -1736,6 +1736,9 @@ redirect_urls = [ "https://example.com/api/auth" ]
       namespace = "my-namespace"
       key = "my-key"
 
+      [[cart_line_properties]]
+      key = "_use_vip_token"
+
       # extra fields not included in the schema should be ignored
       [[invalid_field]]
       namespace = "my-namespace"
@@ -1766,6 +1769,11 @@ redirect_urls = [ "https://example.com/api/auth" ]
             key: 'my-key',
           },
         ],
+        cart_line_properties: [
+          {
+            key: '_use_vip_token',
+          },
+        ],
         input: {
           metafield_identifiers: {
             namespace: 'taxy-tax',
diff --git a/packages/app/src/cli/models/extensions/specifications/tax_calculation.ts b/packages/app/src/cli/models/extensions/specifications/tax_calculation.ts
index 3653cf6b3d..1e97e577bb 100644
--- a/packages/app/src/cli/models/extensions/specifications/tax_calculation.ts
+++ b/packages/app/src/cli/models/extensions/specifications/tax_calculation.ts
@@ -2,6 +2,10 @@ import {createExtensionSpecification} from '../specification.js'
 import {BaseSchema, MetafieldSchema} from '../schemas.js'
 import {zod} from '@shopify/cli-kit/node/schema'
 
+const CartLinePropertySchema = zod.object({
+  key: zod.string(),
+})
+
 const TaxCalculationsSchema = BaseSchema.extend({
   production_api_base_url: zod.string(),
   benchmark_api_base_url: zod.string().optional(),
@@ -17,6 +21,7 @@ const TaxCalculationsSchema = BaseSchema.extend({
     })
     .optional(),
   metafields: zod.array(MetafieldSchema).optional(),
+  cart_line_properties: zod.array(CartLinePropertySchema).optional(),
 })
 
 const spec = createExtensionSpecification({
@@ -30,6 +35,7 @@ const spec = createExtensionSpecification({
       benchmark_api_base_url: config.benchmark_api_base_url,
       calculate_taxes_api_endpoint: config.calculate_taxes_api_endpoint,
       metafields: config.metafields,
+      cart_line_properties: config.cart_line_properties,
       api_version: config.api_version,
       metafield_identifiers: config.input?.metafield_identifiers,
     }