diff --git a/const.go b/const.go
index 60b0dcb..feec746 100644
--- a/const.go
+++ b/const.go
@@ -76,4 +76,26 @@ const (
 type CaptureType string
 const (
 	CaptureTypeOutstandingBalance CaptureType = "OUTSTANDING_BALANCE"
+)
+
+type ProductType     string
+type ProductCategory string //Doc: https://developer.paypal.com/docs/api/catalog-products/v1/#definition-product_category
+const (
+	ProductTypePhysical ProductType = "PHYSICAL"
+	ProductTypeDigital  ProductType = "DIGITAL"
+	ProductTypeService  ProductType = "SERVICE"
+
+	ProductCategorySoftware                                  ProductCategory = "SOFTWARE"
+	ProductCategorySoftwareComputerAndDataProcessingServices ProductCategory = "COMPUTER_AND_DATA_PROCESSING_SERVICES"
+	ProductCategorySoftwareDigitalGames               ProductCategory = "DIGITAL_GAMES"
+	ProductCategorySoftwareGameSoftware               ProductCategory = "GAME_SOFTWARE"
+	ProductCategorySoftwareGames                      ProductCategory = "GAMES"
+	ProductCategorySoftwareGeneral                    ProductCategory = "GENERAL"
+	ProductCategorySoftwareGraphicAndCommercialDesign ProductCategory = "GRAPHIC_AND_COMMERCIAL_DESIGN"
+	ProductCategorySoftwareOemSoftware                ProductCategory = "OEM_SOFTWARE"
+	ProductCategorySoftwareOnlineGaming               ProductCategory = "ONLINE_GAMING"
+	ProductCategorySoftwareOnlineGamingCurrency       ProductCategory = "ONLINE_GAMING_CURRENCY"
+	ProductCategorySoftwareOnlineServices             ProductCategory = "ONLINE_SERVICES"
+	ProductCategorySoftwareOther                      ProductCategory = "OTHER"
+	ProductCategorySoftwareServices                   ProductCategory = "SERVICES"
 )
\ No newline at end of file
diff --git a/integration_test.go b/integration_test.go
index b0c2c38..c39246b 100644
--- a/integration_test.go
+++ b/integration_test.go
@@ -226,8 +226,8 @@ func TestProduct(t *testing.T) {
 	productData := Product{
 		Name:        "Test Product",
 		Description: "A Test Product",
-		Category:    PRODUCT_CATEGORY_SOFTWARE,
-		Type:        PRODUCT_TYPE_SERVICE,
+		Category:    ProductCategorySoftware,
+		Type:        ProductTypeService,
 		ImageUrl:    "https://example.com/image.png",
 		HomeUrl:     "https://example.com",
 	}
diff --git a/products.go b/products.go
index 61e0367..1376a94 100644
--- a/products.go
+++ b/products.go
@@ -6,9 +6,6 @@ import (
 )
 
 type (
-	ProductType     string
-	ProductCategory string
-
 	// Product struct
 	Product struct {
 		ID          string          `json:"id,omitempty"`
@@ -60,13 +57,7 @@ func (self *Product) GetUpdatePatch() []Patch {
 	}
 }
 
-const (
-	PRODUCT_TYPE_PHYSICAL ProductType = "PHYSICAL"
-	PRODUCT_TYPE_DIGITAL  ProductType = "DIGITAL"
-	PRODUCT_TYPE_SERVICE  ProductType = "SERVICE"
 
-	PRODUCT_CATEGORY_SOFTWARE ProductCategory = "software"
-)
 
 // CreateProduct creates a product
 // Doc: https://developer.paypal.com/docs/api/catalog-products/v1/#products_create
diff --git a/subscription_plan.go b/subscription_plan.go
index 30f1a45..9a9b7c9 100644
--- a/subscription_plan.go
+++ b/subscription_plan.go
@@ -13,10 +13,10 @@ type (
 		ProductId          string                 `json:"product_id"`
 		Name               string                 `json:"name"`
 		Status             SubscriptionPlanStatus `json:"status"`
-		Description        SubscriptionPlanStatus `json:"description,omitempty"`
+		Description        string                 `json:"description,omitempty"`
 		BillingCycles      []BillingCycle         `json:"billing_cycles"`
-		PaymentPreferences PaymentPreferences     `json:"payment_preferences"`
-		Taxes              Taxes                  `json:"taxes"`
+		PaymentPreferences *PaymentPreferences    `json:"payment_preferences"`
+		Taxes              *Taxes                  `json:"taxes"`
 		QuantitySupported  bool                   `json:"quantity_supported"` //Indicates whether you can subscribe to this plan by providing a quantity for the goods or service.
 	}
 
@@ -88,35 +88,41 @@ func (self *SubscriptionPlan) GetUpdatePatch() []Patch {
 			Path:      "/description",
 			Value:     self.Description,
 		},
-		{
+	}
+
+	if self.Taxes != nil {
+		result = append(result, Patch{
+			Operation: "replace",
+			Path:      "/taxes/percentage",
+			Value:     self.Taxes.Percentage,
+		})
+	}
+
+	if self.PaymentPreferences != nil {
+		if self.PaymentPreferences.SetupFee != nil {
+			result = append(result, Patch{
+				Operation: "replace",
+				Path:      "/payment_preferences/setup_fee",
+				Value:     self.PaymentPreferences.SetupFee,
+			},
+			)
+		}
+
+		result = append(result, []Patch{{
 			Operation: "replace",
 			Path:      "/payment_preferences/auto_bill_outstanding",
 			Value:     self.PaymentPreferences.AutoBillOutstanding,
 		},
-		{
-			Operation: "replace",
-			Path:      "/payment_preferences/payment_failure_threshold",
-			Value:     self.PaymentPreferences.PaymentFailureThreshold,
-		},
-		{
-			Operation: "replace",
-			Path:      "/payment_preferences/setup_fee_failure_action",
-			Value:     self.PaymentPreferences.SetupFeeFailureAction,
-		},
-		{
-			Operation: "replace",
-			Path:      "/taxes/percentage",
-			Value:     self.Taxes.Percentage,
-		},
-	}
-
-	if self.PaymentPreferences.SetupFee != nil {
-		result = append(result, Patch{
-			Operation: "replace",
-			Path:      "/payment_preferences/setup_fee",
-			Value:     self.PaymentPreferences.SetupFee,
-		},
-		)
+			{
+				Operation: "replace",
+				Path:      "/payment_preferences/payment_failure_threshold",
+				Value:     self.PaymentPreferences.PaymentFailureThreshold,
+			},
+			{
+				Operation: "replace",
+				Path:      "/payment_preferences/setup_fee_failure_action",
+				Value:     self.PaymentPreferences.SetupFeeFailureAction,
+			}}...)
 	}
 
 	return result
@@ -163,9 +169,9 @@ func (c *Client) GetSubscriptionPlan(planId string) (*SubscriptionPlan, error) {
 // List all plans
 // Doc: https://developer.paypal.com/docs/api/subscriptions/v1/#plans_list
 // Endpoint: GET /v1/billing/plans
-func (c *Client) ListSubscriptionPlans(params *SubscriptionPlanListParameters) (*ListProductsResponse, error) {
+func (c *Client) ListSubscriptionPlans(params *SubscriptionPlanListParameters) (*ListSubscriptionPlansResponse, error) {
 	req, err := c.NewRequest(http.MethodGet, fmt.Sprintf("%s%s", c.APIBase, "/v1/billing/plans"), nil)
-	response := &ListProductsResponse{}
+	response := &ListSubscriptionPlansResponse{}
 	if err != nil {
 		return response, err
 	}