diff --git a/dist/lob-api-bundled.yml b/dist/lob-api-bundled.yml
index 1fcf93f8..f31333fc 100644
--- a/dist/lob-api-bundled.yml
+++ b/dist/lob-api-bundled.yml
@@ -8946,6 +8946,7 @@ paths:
               front: tmpl_a1234dddg
               back: tmpl_a1234dddg
               size: 6x9
+              service_request_number: '12345678'
               mail_type: usps_first_class
               merge_variables:
                 name: Harry
@@ -8994,6 +8995,7 @@ paths:
               front: tmpl_c94e83ca2cd5121
               back: tmpl_c94e83ca2cd5121
               size: 6x9
+              service_request_number: '12345678'
               mail_type: usps_first_class
               merge_variables:
                 name: Harry
@@ -9055,6 +9057,7 @@ paths:
               front: tmpl_a1234dddg
               back: tmpl_a1234dddg
               size: 6x9
+              service_request_number: '12345678'
               mail_type: usps_first_class
               merge_variables:
                 name: Harry
@@ -16026,9 +16029,10 @@ components:
             source_material:
               $ref: '#/components/schemas/booklet_source_material'
             failure_reason:
+              type: object
+              nullable: true
               allOf:
                 - $ref: '#/components/schemas/failure_reason'
-                - nullable: true
             object:
               type: string
               description: Value is resource type.
@@ -18391,9 +18395,10 @@ components:
             status:
               $ref: '#/components/schemas/status'
             failure_reason:
+              type: object
+              nullable: true
               allOf:
                 - $ref: '#/components/schemas/failure_reason'
-                - nullable: true
             object:
               type: string
               description: Value is resource type.
@@ -18494,6 +18499,15 @@ components:
         - $ref: '#/components/schemas/tmpl_id'
         - $ref: '#/components/schemas/remote_file_url'
         - $ref: '#/components/schemas/local_file_path'
+    service_request_number:
+      type: string
+      description: |-
+        The service request number (SR#) of an approved USPS promotion (for example, the Integrated Technology promotion) to apply to this mailpiece. Supported on letters, postcards, self mailers, and checks.
+
+        This must be a **top-level** field in the create request, alongside `size`, `front`, and `back` — **not** nested inside `merge_variables` or any other object. A misplaced `service_request_number` is silently ignored: the mailpiece is created successfully with no promotion applied and no error returned.
+
+        The SR# must be approved for your account and cover the resource type, size, and mail type of this mailpiece for the promotion to apply. If omitted, no promotion is applied. See our <a href="https://help.lob.com/print-and-mail/building-a-mail-strategy/usps-promotions-through-lob" target="_blank">guide to USPS promotions through Lob</a> for more information.
+      nullable: true
     check_editable_props:
       allOf:
         - $ref: '#/components/schemas/check_base'
@@ -18562,6 +18576,8 @@ components:
               $ref: '#/components/schemas/billing_group_id'
             use_type:
               $ref: '#/components/schemas/chk_use_type'
+            service_request_number:
+              $ref: '#/components/schemas/service_request_number'
             print_speed:
               $ref: '#/components/schemas/print_speed'
     check_editable:
@@ -19289,9 +19305,10 @@ components:
             status:
               $ref: '#/components/schemas/status'
             failure_reason:
+              type: object
+              nullable: true
               allOf:
                 - $ref: '#/components/schemas/failure_reason'
-                - nullable: true
             object:
               type: string
               description: Value is resource type.
@@ -19687,6 +19704,8 @@ components:
               $ref: '#/components/schemas/qr_code'
             use_type:
               $ref: '#/components/schemas/ltr_use_type'
+            service_request_number:
+              $ref: '#/components/schemas/service_request_number'
             fsc:
               type: boolean
               description: This is in beta. Contact support@lob.com or your account contact to learn more. Not available for `A4` and `us_legal` letter size.
@@ -19767,9 +19786,10 @@ components:
             status:
               $ref: '#/components/schemas/status'
             failure_reason:
+              type: object
+              nullable: true
               allOf:
                 - $ref: '#/components/schemas/failure_reason'
-                - nullable: true
             object:
               type: string
               description: Value is resource type.
@@ -19846,6 +19866,8 @@ components:
               $ref: '#/components/schemas/qr_code'
             use_type:
               $ref: '#/components/schemas/psc_use_type'
+            service_request_number:
+              $ref: '#/components/schemas/service_request_number'
             fsc:
               type: boolean
               description: This is in beta. Contact support@lob.com or your account contact to learn more. Not available for `4x6` or `A5` postcard sizes.
@@ -20326,9 +20348,10 @@ components:
             campaign_id:
               $ref: '#/components/schemas/campaign_id'
             failure_reason:
+              type: object
+              nullable: true
               allOf:
                 - $ref: '#/components/schemas/failure_reason'
-                - nullable: true
     self_mailer_deletion:
       description: Lob uses RESTful HTTP response codes to indicate success or failure of an API request. In general, 2xx indicates success, 4xx indicate an input error, and 5xx indicates an error on Lob's end.
       properties:
@@ -20387,6 +20410,8 @@ components:
               $ref: '#/components/schemas/qr_code'
             use_type:
               $ref: '#/components/schemas/sfm_use_type'
+            service_request_number:
+              $ref: '#/components/schemas/service_request_number'
             fsc:
               type: boolean
               description: This is in beta. Contact support@lob.com or your account contact to learn more. Not available for `11x9_bifold` self-mailer size.
@@ -20479,9 +20504,10 @@ components:
             campaign_id:
               $ref: '#/components/schemas/campaign_id'
             failure_reason:
+              type: object
+              nullable: true
               allOf:
                 - $ref: '#/components/schemas/failure_reason'
-                - nullable: true
             color:
               $ref: '#/components/schemas/color'
     snap_pack_deletion:
diff --git a/resources/checks/models/check_editable_props.yml b/resources/checks/models/check_editable_props.yml
index eb67bfab..4031a8da 100644
--- a/resources/checks/models/check_editable_props.yml
+++ b/resources/checks/models/check_editable_props.yml
@@ -98,5 +98,8 @@ allOf:
       use_type:
         $ref: "../attributes/chk_use_type.yml"
 
+      service_request_number:
+        $ref: "../../../shared/attributes/service_request_number.yml"
+
       print_speed:
         $ref: "../../../shared/attributes/print_speed.yml"
diff --git a/resources/letters/models/letter_editable.yml b/resources/letters/models/letter_editable.yml
index 42e45377..efa6dd39 100644
--- a/resources/letters/models/letter_editable.yml
+++ b/resources/letters/models/letter_editable.yml
@@ -67,6 +67,9 @@ allOf:
       use_type:
         $ref: "../attributes/ltr_use_type.yml"
 
+      service_request_number:
+        $ref: "../../../shared/attributes/service_request_number.yml"
+
       fsc:
         type: boolean
         description: This is in beta. Contact support@lob.com or your account contact to learn more. Not available for `A4` and `us_legal` letter size.
diff --git a/resources/postcards/models/postcard_editable.yml b/resources/postcards/models/postcard_editable.yml
index 7314ba16..07609dff 100644
--- a/resources/postcards/models/postcard_editable.yml
+++ b/resources/postcards/models/postcard_editable.yml
@@ -27,6 +27,9 @@ allOf:
       use_type:
         $ref: "../attributes/psc_use_type.yml"
 
+      service_request_number:
+        $ref: "../../../shared/attributes/service_request_number.yml"
+
       fsc: # Forest Stewardship Council
         type: boolean
         description: This is in beta. Contact support@lob.com or your account contact to learn more. Not available for `4x6` or `A5` postcard sizes.
diff --git a/resources/postcards/postcards.yml b/resources/postcards/postcards.yml
index f211f69a..93277c67 100644
--- a/resources/postcards/postcards.yml
+++ b/resources/postcards/postcards.yml
@@ -212,6 +212,7 @@ post:
           front: tmpl_a1234dddg
           back: tmpl_a1234dddg
           size: "6x9"
+          service_request_number: "12345678"
           mail_type: usps_first_class
           merge_variables:
             name: Harry
@@ -261,6 +262,7 @@ post:
           front: tmpl_c94e83ca2cd5121
           back: tmpl_c94e83ca2cd5121
           size: "6x9"
+          service_request_number: "12345678"
           mail_type: usps_first_class
           merge_variables:
             name: Harry
@@ -323,6 +325,7 @@ post:
           front: tmpl_a1234dddg
           back: tmpl_a1234dddg
           size: "6x9"
+          service_request_number: "12345678"
           mail_type: usps_first_class
           merge_variables:
             name: Harry
diff --git a/resources/self_mailers/models/self_mailer_editable.yml b/resources/self_mailers/models/self_mailer_editable.yml
index aac697c2..025f019d 100644
--- a/resources/self_mailers/models/self_mailer_editable.yml
+++ b/resources/self_mailers/models/self_mailer_editable.yml
@@ -67,6 +67,9 @@ allOf:
       use_type:
         $ref: "../attributes/sfm_use_type.yml"
 
+      service_request_number:
+        $ref: "../../../shared/attributes/service_request_number.yml"
+
       fsc:
         type: boolean
         description: This is in beta. Contact support@lob.com or your account contact to learn more. Not available for `11x9_bifold` self-mailer size.
diff --git a/shared/attributes/service_request_number.yml b/shared/attributes/service_request_number.yml
new file mode 100644
index 00000000..4e4c2c65
--- /dev/null
+++ b/shared/attributes/service_request_number.yml
@@ -0,0 +1,22 @@
+type: string
+
+description: >-
+  The service request number (SR#) of an approved USPS promotion (for example,
+  the Integrated Technology promotion) to apply to this mailpiece. Supported on
+  letters, postcards, self mailers, and checks.
+
+
+  This must be a **top-level** field in the create request, alongside `size`,
+  `front`, and `back` — **not** nested inside `merge_variables` or any other
+  object. A misplaced `service_request_number` is silently ignored: the
+  mailpiece is created successfully with no promotion applied and no error
+  returned.
+
+
+  The SR# must be approved for your account and cover the resource type, size,
+  and mail type of this mailpiece for the promotion to apply. If omitted, no
+  promotion is applied. See our
+  <a href="https://help.lob.com/print-and-mail/building-a-mail-strategy/usps-promotions-through-lob" target="_blank">guide to USPS promotions through Lob</a>
+  for more information.
+
+nullable: true