diff --git a/internal/modules/expenses/services/expense.service.go b/internal/modules/expenses/services/expense.service.go
index dbfb00c2..24ba4f2e 100644
--- a/internal/modules/expenses/services/expense.service.go
+++ b/internal/modules/expenses/services/expense.service.go
@@ -213,7 +213,7 @@ func (s *expenseService) CreateOne(c *fiber.Ctx, req *validation.Create) (*expen
 
 				var projectFlockKandangId *uint64
 
-				if req.Category == "BOP" {
+				if req.Category == string(utils.ExpenseCategoryBOP) {
 
 					projectFlockKandang, err := projectFlockKandangRepoTx.GetActiveByKandangID(c.Context(), uint(expenseNonstock.KandangID))
 					if err != nil {
@@ -230,10 +230,10 @@ func (s *expenseService) CreateOne(c *fiber.Ctx, req *validation.Create) (*expen
 
 					nonstockId := costItem.NonstockID
 					var kandangId *uint64
-					if req.Category == "NON-BOP" {
+					if req.Category == string(utils.ExpenseCategoryNonBOP) {
 						id := uint64(expenseNonstock.KandangID)
 						kandangId = &id
-					} else if req.Category == "BOP" {
+					} else if req.Category == string(utils.ExpenseCategoryBOP) {
 						if projectFlockKandangId != nil {
 							kandangId = &expenseNonstock.KandangID
 						}
@@ -385,7 +385,7 @@ func (s expenseService) UpdateOne(c *fiber.Ctx, req *validation.Update, id uint)
 		}
 
 		if categoryChanged {
-			if currentExpense.Category == "BOP" && newCategory == "NON-BOP" {
+			if currentExpense.Category == string(utils.ExpenseCategoryBOP) && newCategory == string(utils.ExpenseCategoryNonBOP) {
 
 				var existingExpenseNonstocks []entity.ExpenseNonstock
 				if err := tx.Where("expense_id = ?", id).Find(&existingExpenseNonstocks).Error; err != nil {
@@ -400,7 +400,7 @@ func (s expenseService) UpdateOne(c *fiber.Ctx, req *validation.Update, id uint)
 						return fiber.NewError(fiber.StatusInternalServerError, "Failed to update project flock kandang id to null")
 					}
 				}
-			} else if currentExpense.Category == "NON-BOP" && newCategory == "BOP" {
+			} else if currentExpense.Category == string(utils.ExpenseCategoryNonBOP) && newCategory == string(utils.ExpenseCategoryBOP) {
 
 				var existingExpenseNonstocks []entity.ExpenseNonstock
 				if err := tx.Where("expense_id = ?", id).Find(&existingExpenseNonstocks).Error; err != nil {
@@ -457,7 +457,7 @@ func (s expenseService) UpdateOne(c *fiber.Ctx, req *validation.Update, id uint)
 			for _, expenseNonstock := range *req.ExpenseNonstocks {
 				var projectFlockKandangId *uint64
 
-				if updatedExpense.Category == "BOP" {
+				if updatedExpense.Category == string(utils.ExpenseCategoryBOP) {
 					projectFlockKandangRepoTx := projectFlockKandangRepo.NewProjectFlockKandangRepository(tx)
 					projectFlockKandang, err := projectFlockKandangRepoTx.GetActiveByKandangID(c.Context(), uint(expenseNonstock.KandangID))
 					if err != nil {
@@ -480,10 +480,10 @@ func (s expenseService) UpdateOne(c *fiber.Ctx, req *validation.Update, id uint)
 					}
 
 					var kandangId *uint64
-					if updatedExpense.Category == "NON-BOP" {
+					if updatedExpense.Category == string(utils.ExpenseCategoryNonBOP) {
 						id := uint64(expenseNonstock.KandangID)
 						kandangId = &id
-					} else if updatedExpense.Category == "BOP" {
+					} else if updatedExpense.Category == string(utils.ExpenseCategoryBOP) {
 						if projectFlockKandangId != nil {
 							kandangId = &expenseNonstock.KandangID
 						}
diff --git a/internal/utils/constant.go b/internal/utils/constant.go
index d4f6ec02..85b33f9b 100644
--- a/internal/utils/constant.go
+++ b/internal/utils/constant.go
@@ -135,6 +135,17 @@ const (
 	SupplierCategorySapronak SupplierCategory = "SAPRONAK"
 )
 
+// -------------------------------------------------------------------
+// ExpenseCategory
+// -------------------------------------------------------------------
+
+type ExpenseCategory string
+
+const (
+	ExpenseCategoryBOP    ExpenseCategory = "BOP"
+	ExpenseCategoryNonBOP ExpenseCategory = "NON-BOP"
+)
+
 // -------------------------------------------------------------------
 // Kandang Status
 // -------------------------------------------------------------------
@@ -429,6 +440,14 @@ func IsValidSupplierCategory(v string) bool {
 	return false
 }
 
+func IsValidExpenseCategory(v string) bool {
+	switch ExpenseCategory(v) {
+	case ExpenseCategoryBOP, ExpenseCategoryNonBOP:
+		return true
+	}
+	return false
+}
+
 // example use
 
 // Recording helper