begin_checkout

The begin_checkout event marks the moment a user crosses from browsing and cart management into the checkout funnel. It’s a high-intent signal and the gate event for your checkout funnel analysis in GA4. Every checkout step event that follows — add_shipping_info, add_payment_info, purchase — should have consistent cart data, starting with what you push here.

When to fire

Fire begin_checkout when:

• The user clicks the “Checkout” or “Proceed to Checkout” button
• The checkout page first loads (for multi-page checkouts)
• The user enters step 1 of a single-page checkout form

Do not fire multiple times if the user navigates back and forward through checkout steps. begin_checkout is the initiation event — it fires once per checkout session.

Complete dataLayer push

// Always clear previous ecommerce data first
dataLayer.push({ ecommerce: null });

dataLayer.push({
  event: 'begin_checkout',
  ecommerce: {
    currency: 'USD',
    value: 174.47,
    coupon: 'SUMMER15',    // order-level coupon if applied
    items: [
      {
        item_id: 'SKU-001-BLK-L',
        item_name: 'Classic Leather Jacket',
        item_brand: 'Heritage Co.',
        item_category: 'Apparel',
        item_category2: 'Outerwear',
        item_variant: 'Black / Large',
        price: 89.99,
        quantity: 1,
        coupon: 'SUMMER15',    // item-level coupon if different from order coupon
        discount: 13.50,
        affiliation: 'Online Store'
      },
      {
        item_id: 'SKU-047-WHT-M',
        item_name: 'Cotton Crew T-Shirt',
        item_brand: 'Heritage Co.',
        item_category: 'Apparel',
        item_category2: 'Tops',
        item_variant: 'White / Medium',
        price: 24.99,
        quantity: 2,
        coupon: '',
        discount: 0,
        affiliation: 'Online Store'
      },
      {
        item_id: 'SKU-112-TAN-34',
        item_name: 'Woven Leather Belt',
        item_brand: 'Heritage Co.',
        item_category: 'Accessories',
        item_category2: 'Belts',
        item_variant: 'Tan / 34',
        price: 34.50,
        quantity: 1,
        coupon: '',
        discount: 0,
        affiliation: 'Online Store'
      }
    ]
  }
});

Note

The coupon parameter appears at two levels. ecommerce.coupon is the order-level coupon code (applies to the whole order). items[].coupon is an item-level coupon if specific items have individual discount codes. In most implementations, both carry the same code when one coupon applies to the whole cart. Include an empty string if no coupon is applied.

Event schema

Event Schema begin_checkout

Parameter	Type	Required	Description
event	string	Required	Must be "begin_checkout"
ecommerce.currency	string	Required	ISO 4217 currency code.
ecommerce.value	number	Required	Cart total — sum of (price × quantity) for all items, after any discounts.
ecommerce.coupon	string	Optional	Order-level coupon code if one has been applied.
ecommerce.items[]	Array<Item>	Required	All items in the cart at checkout initiation.
items[].item_id	string	Required	SKU or variant-level product identifier.
items[].item_name	string	Required	Product name.
items[].item_brand	string	Optional	Brand or manufacturer.
items[].item_category	string	Optional	Primary product category.
items[].item_variant	string	Optional	Selected variant.
items[].price	number	Optional	Unit price.
items[].quantity	number	Optional	Quantity in cart.
items[].coupon	string	Optional	Item-level coupon code.
items[].discount	number	Optional	Monetary discount applied to this item.
items[].affiliation	string	Optional	Store or seller affiliation.

GTM configuration

1. Create a Custom Event trigger. Event name: begin_checkout. Name it CE - begin_checkout.

2. Create Data Layer Variables for ecommerce.currency, ecommerce.value, ecommerce.coupon, and ecommerce.items.

3. Create the GA4 Event tag. Event name: begin_checkout. Enable Send Ecommerce data. Add currency, value, and coupon as explicit event parameters.

4. Test in Preview mode. Add items to cart, apply a coupon, then click Checkout. Verify the coupon code appears at both the event and item levels, and that the value reflects post-discount pricing.

Common mistakes

Firing on every checkout page navigation. If checkout is multi-page and the user goes back to cart and re-initiates checkout, should begin_checkout fire again? Technically yes — it’s a new checkout initiation. But if your site counts each browser-forward click on the checkout button as a new session, use a sessionStorage flag to prevent duplicate fires within the same checkout attempt.

Not including coupon data. The coupon parameter is one of the most valuable fields for promotion analysis. If you have a coupon system, always include the active coupon code. An empty string for no coupon is fine and expected.

Inconsistent cart value between view_cart and begin_checkout. If the user doesn’t change their cart between viewing it and clicking Checkout, these values should match. Discrepancies signal a calculation bug.

view_cart The event that precedes begin_checkout — cart page view.

add_shipping_info The next checkout step — shipping method selection.

purchase The final checkout event — order confirmation.