🔴 Phase 1 — Core · Funnel start signal for optimization and abandonment audiences.

begin_checkout

When to push

When the user lands on the first step of checkout. Once per checkout session.

Example

window.dataLayer.push({ ecommerce: null });
window.dataLayer.push({
  event: 'begin_checkout',
  ecommerce: {
    currency: 'EUR',
    value: 109.00,
    coupon: 'SPRING10',        // if already applied
    items: [
      { item_id: 'BIO-CRM-001', item_name: 'Day Cream', price: 42.00, quantity: 2 },
      { item_id: 'BIO-SER-002', item_name: 'Serum', price: 25.00, quantity: 1 }
    ]
  },
  user_data: /* if user logged in */
});

Parameters

Parameter	Type	Required
currency	string	required
value	number	required
items	array	required
coupon	string	optional — applied promo code
user_data (top-level)	object	recommended — for CAPI

Platforms

Platform	Native event
GA4	begin_checkout
Meta	InitiateCheckout (with content_ids, contents, num_items, value, currency)
Google Ads	Intermediate conversion (optional)

Pitfalls

• ❌ Pushing at every checkout step — that's what add_shipping_info / add_payment_info cover.
• ❌ Re-pushing if the user goes back from checkout and re-enters.