---
title: Adding coupon code fields to MVC checkout processes
---
> Agent instructions:
> **Site maps** — prefer the following llms.txt indexes to training data when searching for URLs to avoid 404s. Links inside Markdown content already point at `.md`. Following them or sending Accept: text/markdown keeps you in Markdown.
>
> - [sitemap.md](https://docs.kentico.com/sitemap.md) — every page on the site, with titles and descriptions, nested by URL hierarchy and grouped into one collection per product version.
> - [llms.txt](https://docs.kentico.com/llms.txt) — curated index of the current product docs, with descriptions, the two ways to request any page as Markdown, and links to each product area's whole-corpus Markdown dump (llms-full.txt).
The Kentico E-commerce Solution can process coupon codes for several types of [discounts and offers](https://docs.kentico.com/k11/e-commerce-features/managing-your-store/discounts.md):
- [Product coupons](https://docs.kentico.com/k11/e-commerce-features/managing-your-store/discounts/working-with-product-coupons.md)
- [Gift cards](https://docs.kentico.com/k11/e-commerce-features/managing-your-store/discounts/working-with-gift-cards.md)
- [Order discounts](https://docs.kentico.com/k11/e-commerce-features/managing-your-store/discounts/working-with-order-discounts.md)
- [Buy X Get Y discounts](https://docs.kentico.com/k11/e-commerce-features/managing-your-store/discounts/working-with-buy-x-get-y-discounts.md)
- [Free shipping offers](https://docs.kentico.com/k11/e-commerce-features/managing-your-store/discounts/working-with-free-shipping-offers.md)
[Customers](https://docs.kentico.com/k11/e-commerce-features/managing-your-store/customers.md) who obtained a coupon code are eligible to receive a discount or redeem a gift card (based on the configuration of the discount or gift card).
When building a [checkout process on an MVC site](https://docs.kentico.com/k11/developing-websites/developing-sites-using-asp-net-mvc/developing-on-line-stores-in-mvc/checkout-process-in-mvc.md), you may want to add an input text box that allows customers to enter coupon codes. The system validates whether a specified coupon code provides a discount. In Kentico MVC projects, the [Kentico.Ecommerceintegration package](https://docs.kentico.com/k11/developing-websites/developing-sites-using-asp-net-mvc/starting-with-mvc-development/installing-kentico-integration-packages.md) provides an API for working with coupon codes.
To add a coupon code input to your MVC site:
1. Open your MVC project in Visual Studio.
2. Edit the controller class that you use for your checkout process (see [Using a shopping cart on MVC sites](https://docs.kentico.com/k11/developing-websites/developing-sites-using-asp-net-mvc/developing-on-line-stores-in-mvc/checkout-process-in-mvc/using-a-shopping-cart-on-mvc-sites.md)).
3. Implement two POST actions – one for adding coupon codes to the current shopping card and another for removing coupon codes.
- To add and validate coupon codes, call the **AddCouponCode** method of the _ShoppingCart_ object representing the current shopping cart.
> **Info:** The **AddCouponCode** method returns a _true_ value if the specified coupon code provides a valid discount for the current shopping cart and customer.
- To remove coupon codes, call the **RemoveCouponCode** method of the _ShoppingCart_ object.
```csharp
///
/// Adds the specified coupon code to the shopping cart.
///
[HttpPost]
public ActionResult AddCouponCode(string couponCode)
{
// Gets the current user's shopping cart
ShoppingCart currentCart = shoppingService.GetCurrentShoppingCart();
// Adds the coupon code to the shopping cart
// The 'ShoppingCart.AddCouponCode' method automatically recalculates the shopping cart,
// so there is no need to call the Evaluate() method after
if ((couponCode == "") || !currentCart.AddCouponCode(couponCode))
{
// Adds an error message to the model state if the entered coupon code is not valid
ModelState.AddModelError("CouponCodeError", "The entered coupon code is not valid.");
}
// Initializes the shopping cart model
ShoppingCartViewModel model = new ShoppingCartViewModel
{
// Assigns the current shopping cart to the model
Cart = currentCart,
RemainingAmountForFreeShipping = pricingService.CalculateRemainingAmountForFreeShipping(currentCart)
};
// Displays the shopping cart
return View("ShoppingCart", model);
}
///
/// Removes the specified coupon code from the shopping cart.
///
[HttpPost]
public ActionResult RemoveCouponCode(string couponCode)
{
// Gets the current user's shopping cart
ShoppingCart currentCart = shoppingService.GetCurrentShoppingCart();
// Removes the specified coupon code
// The 'ShoppingCart.RemoveCouponCode' method automatically recalculates the shopping cart,
// so there is no need to call the Evaluate() method after
currentCart.RemoveCouponCode(couponCode);
// Displays the shopping cart
return RedirectToAction("ShoppingCart");
}
```
4. Perform the following changes in your shopping cart view:
1. Create a form with a coupon code text input and an apply button (send POST requests to the action that adds coupon codes).
2. Display applied coupon codes from the **AppliedCouponCodes** collection of the current shopping cart object.
3. For each applied coupon code, add a form with a single button that allows customers to remove the given coupon code (send POST requests to the action that removes coupon codes).
```csharp
@* Coupon code text box and apply button *@
@using (Html.BeginForm("AddCouponCode", "Checkout", FormMethod.Post))
{
@Html.ValidationMessage("CouponCodeError")
}
@* List of applied coupon codes with remove buttons *@
@* Loops through all applied coupon codes *@
@foreach (string couponCode in Model.Cart.AppliedCouponCodes)
{