begin_checkout is the Google Analytics 4 event that records a shopper starting the checkout process, usually by pressing the checkout button in their basket. It marks the point where someone stops browsing and starts trying to pay, which makes it the opening step of any checkout funnel.
How begin_checkout works
Like the other ecommerce events, begin_checkout is a recommended event that your site has to send. It carries the basket contents in an items list, the basket value, the currency (GBP for a UK shop) and any coupon already applied.
There are two common ways to fire it. One is on the click of the checkout button; the other is when the first checkout page loads. The page-load version is usually more accurate, because it only counts people who actually reached checkout. If shoppers can also jump straight to checkout from a mini-basket or an express payment button, each route needs to send the event too.
Hosted checkouts need extra thought. On Shopify, the checkout runs on Shopify’s own pages, and at the time of writing (October 2026) events there are collected through Shopify’s customer events system or its Google app rather than through a normal Tag Manager container. Shops that hand shoppers to a third-party payment page, such as some PayPal flows, may lose sight of them between begin_checkout and the return to the order confirmation page.
Why it matters
begin_checkout divides your losses into two groups. People who add to basket but never begin checkout are hesitating over the purchase itself: price, delivery, comparison shopping or simply saving items for later. People who begin checkout but never buy have decided to buy and then run into something. That second group is the more valuable to fix, because their intent is already proven.
Your checkout abandonment rate is calculated from exactly this event: the share of checkouts started that do not end in a purchase. For many UK shops the usual causes are familiar: forced account creation, surprise delivery charges, a lack of preferred payment methods such as PayPal or Apple Pay, or a form that fights with autofill on mobile.
The event also feeds advertising. Checkout starters make a strong remarketing audience, and an abandoned-checkout email is one of the few automated emails most shoppers expect and act on, provided you have their email address and permission to send it under PECR.
Common mistakes
- Firing on every load of the checkout page So a shopper who refreshes or goes back and forth counts as several checkouts.
- Missing express routes such as Apple Pay or PayPal buttons on product pages, which bypass the main checkout button entirely.
- Sending an empty items list Which leaves product-level checkout reports blank.
- Counting begin_checkout as a conversion in Google Ads or GA4 alongside purchases, which double counts success and confuses bidding.
- Ignoring the payment-page gap Where shoppers leave for an external payment provider and return as a referral from that provider, stealing credit from the real source until you add its domain to your referral exclusions.
How to act on it
Place a test order by every route a real customer might take, and watch begin_checkout in GA4 DebugView. You want exactly one event per checkout started, with the items and value matching the basket.
Then add steps after it. Pairing begin_checkout with add_shipping_info and add_payment_info splits checkout into stages, so a funnel exploration shows precisely where people stop. Compare mobile with desktop: if mobile abandonment is far worse, the checkout form is usually the problem rather than the offer.
Finally, keep purchase as your only primary conversion in ad platforms. Checkout starts belong in audiences and diagnostics, not in bidding targets. This is the kind of measurement clean-up I do early in performance marketing work, before spending more on traffic.