diff --git a/app/controllers/api/v1/customers_controller.rb b/app/controllers/api/v1/customers_controller.rb
index da3037ff75..3a5dc0cc44 100644
--- a/app/controllers/api/v1/customers_controller.rb
+++ b/app/controllers/api/v1/customers_controller.rb
@@ -107,17 +107,25 @@ module Api
             street_address_1: :address1, street_address_2: :address2,
             postal_code: :zipcode,
             locality: :city,
-            region: :state_name,
+            region: :state,
             country: :country,
           }.with_indifferent_access[key]
         end
 
-        if address[:state_name].present?
-          address[:state] = Spree::State.find_by(name: address[:state_name][:name])
+        if address[:state].present?
+          address[:state] = Spree::State.find_by(
+            "LOWER(abbr) = ? OR LOWER(name) = ?",
+            address.dig(:state, :code)&.downcase,
+            address.dig(:state, :name)&.downcase,
+          )
         end
 
         if address[:country].present?
-          address[:country] = Spree::Country.find_by(name: address[:country][:name])
+          address[:country] = Spree::Country.find_by(
+            "LOWER(iso) = ? OR LOWER(name) = ?",
+            address.dig(:country, :code)&.downcase,
+            address.dig(:country, :name)&.downcase,
+          )
         end
 
         attributes["#{to}_attributes"] = address
diff --git a/app/json_schemas/customer_schema.rb b/app/json_schemas/customer_schema.rb
index 264caf93fc..ecced41793 100644
--- a/app/json_schemas/customer_schema.rb
+++ b/app/json_schemas/customer_schema.rb
@@ -42,7 +42,7 @@ class CustomerSchema < JsonApiSchema
       postal_code: "1234",
       locality: "Melbourne",
       region: { code: "Vic", name: "Victoria" },
-      country: { code: "AUS", name: "Australia" },
+      country: { code: "AU", name: "Australia" },
     }
   end
 
diff --git a/app/serializers/api/v1/address_serializer.rb b/app/serializers/api/v1/address_serializer.rb
index 91dff2d701..72b800e960 100644
--- a/app/serializers/api/v1/address_serializer.rb
+++ b/app/serializers/api/v1/address_serializer.rb
@@ -20,7 +20,7 @@ module Api
       attribute :country do |object|
         {
           name: object.country.name,
-          code: object.country.iso3,
+          code: object.country.iso,
         }
       end
     end
diff --git a/spec/requests/api/v1/customers_spec.rb b/spec/requests/api/v1/customers_spec.rb
index 58ae41945d..047c5e0438 100644
--- a/spec/requests/api/v1/customers_spec.rb
+++ b/spec/requests/api/v1/customers_spec.rb
@@ -302,6 +302,59 @@ describe "Customers", type: :request do
         end
       end
 
+      describe "address" do
+        it "matches by country and state code" do
+          put "/api/v1/customers/#{customer1.id}", params: {
+            customer: {
+              shipping_address: CustomerSchema.address_example.merge(
+                region: { code: "Vic" },
+                country: { code: "AU" },
+              ),
+            }
+          }
+
+          expect(response).to have_http_status :ok
+          expect(json_response.dig(:data, :attributes, :shipping_address)).to include(
+            region: { code: "Vic", name: "Victoria" },
+            country: { code: "AU", name: "Australia" },
+          )
+        end
+
+        it "matches by country and state name" do
+          put "/api/v1/customers/#{customer1.id}", params: {
+            customer: {
+              shipping_address: CustomerSchema.address_example.merge(
+                region: { name: "Victoria" },
+                country: { name: "Australia" },
+              ),
+            }
+          }
+
+          expect(response).to have_http_status :ok
+          expect(json_response.dig(:data, :attributes, :shipping_address)).to include(
+            region: { code: "Vic", name: "Victoria" },
+            country: { code: "AU", name: "Australia" },
+          )
+        end
+
+        it "matches country and state case-insensitive" do
+          put "/api/v1/customers/#{customer1.id}", params: {
+            customer: {
+              shipping_address: CustomerSchema.address_example.merge(
+                region: { code: "VIC" },
+                country: { name: "AUSTRALIA" },
+              ),
+            }
+          }
+
+          expect(response).to have_http_status :ok
+          expect(json_response.dig(:data, :attributes, :shipping_address)).to include(
+            region: { code: "Vic", name: "Victoria" },
+            country: { code: "AU", name: "Australia" },
+          )
+        end
+      end
+
       response "422", "Unprocessable entity" do
         param(:id) { customer1.id }
         param(:customer) { {} }
diff --git a/swagger/v1/swagger.yaml b/swagger/v1/swagger.yaml
index 911fa13e74..2909306e6e 100644
--- a/swagger/v1/swagger.yaml
+++ b/swagger/v1/swagger.yaml
@@ -91,8 +91,12 @@ components:
                     street_address_2: ''
                     postal_code: '1234'
                     locality: Melbourne
-                    region: Victoria
-                    country: Australia
+                    region:
+                      code: Vic
+                      name: Victoria
+                    country:
+                      code: AU
+                      name: Australia
               required:
               - id
               - enterprise_id
@@ -200,8 +204,12 @@ components:
                       street_address_2: ''
                       postal_code: '1234'
                       locality: Melbourne
-                      region: Victoria
-                      country: Australia
+                      region:
+                        code: Vic
+                        name: Victoria
+                      country:
+                        code: AU
+                        name: Australia
                 required:
                 - id
                 - enterprise_id
@@ -372,8 +380,12 @@ paths:
                     street_address_2: ''
                     postal_code: '1234'
                     locality: Melbourne
-                    region: Victoria
-                    country: Australia
+                    region:
+                      code: Vic
+                      name: Victoria
+                    country:
+                      code: AU
+                      name: Australia
               required:
               - enterprise_id
               - email
@@ -478,8 +490,12 @@ paths:
                     street_address_2: ''
                     postal_code: '1234'
                     locality: Melbourne
-                    region: Victoria
-                    country: Australia
+                    region:
+                      code: Vic
+                      name: Victoria
+                    country:
+                      code: AU
+                      name: Australia
               required:
               - enterprise_id
               - email