user_data — user identifiers for matching

user_data parameters are critical for the quality of signal sent to Meta CAPI and Google Ads Enhanced Conversions. They allow Meta/Google to match the event to a user account and attribute conversions correctly.

When to include user_data

Event	user_data
purchase	REQUIRED — send everything you have
begin_checkout, add_shipping_info, add_payment_info	If user logged in or fields filled
generate_lead, sign_up	REQUIRED
add_to_cart, view_item, etc.	If user logged in
page_view	If user logged in

The more identity signals you send (and the earlier in the funnel), the better the Meta matching and the more accurate the Google Ads attribution.

Send values in plain text — do not hash

⚠️ Important: send user_data values in plain text. GTM Server hashes them with SHA-256 before sending to Meta. If you hash on the front-end, you'll hash twice → matching breaks.

window.dataLayer.push({
  event: 'purchase',
  ecommerce: { /* ... */ },
  user_data: {
    email: 'jane.doe@example.com',
    phone: '+33612345678',           // E.164 ideal
    first_name: 'Jane',
    last_name: 'Doe',
    address: {
      street: '12 Lilac Street',
      city: 'Paris',
      region: 'IDF',                 // state / region
      postal_code: '75011',
      country: 'FR'                  // ISO 3166-1 alpha-2
    },
    external_id: 'user_12345',       // internal DB ID (anonymized OK)
    date_of_birth: '1990-04-15',     // YYYY-MM-DD
    gender: 'f'                      // 'm' / 'f'
  }
});

Supported fields

Field	Format	Maps to Meta	Maps to GAds
email	lowercase, trimmed	em	email
phone	E.164 with or without +	ph	phone_number
first_name	string	fn	first_name
last_name	string	ln	last_name
date_of_birth	YYYY-MM-DD	db (→ YYYYMMDD)	—
gender	'm' or 'f'	ge	—
address.street	string	—	street_address
address.city	string	ct	city
address.region	string	st	region
address.postal_code	string	zp	postal_code
address.country	ISO alpha-2 ('FR')	country	country
external_id	string	external_id	—

Normalize before pushing

GTM Server normalizes + hashes, but you can boost match quality by:

{
  email: rawEmail.trim().toLowerCase(),
  phone: rawPhone.replace(/[^\d]/g, ''),     // digits only, e.g. "33612345678"
  first_name: firstName.trim().toLowerCase(),
  last_name: lastName.trim().toLowerCase(),
  address: {
    city: city.trim().toLowerCase(),
    postal_code: postalCode.replace(/\s/g, ''),
    country: country.toUpperCase()
  }
}

Helper

function buildUserData(customer) {
  if (!customer) return undefined;
  const ud = {};
  if (customer.email) ud.email = customer.email.trim().toLowerCase();
  if (customer.phone) ud.phone = customer.phone.replace(/[^\d+]/g, '');
  if (customer.firstName) ud.first_name = customer.firstName.trim().toLowerCase();
  if (customer.lastName) ud.last_name = customer.lastName.trim().toLowerCase();
  if (customer.id) ud.external_id = String(customer.id);
  if (customer.birthDate) ud.date_of_birth = customer.birthDate; // YYYY-MM-DD
  if (customer.gender) ud.gender = customer.gender.toLowerCase().startsWith('f') ? 'f' : 'm';

  if (customer.address) {
    ud.address = {};
    if (customer.address.street) ud.address.street = customer.address.street.trim().toLowerCase();
    if (customer.address.city) ud.address.city = customer.address.city.trim().toLowerCase();
    if (customer.address.region) ud.address.region = customer.address.region.trim().toLowerCase();
    if (customer.address.postalCode) ud.address.postal_code = customer.address.postalCode.replace(/\s/g, '');
    if (customer.address.country) ud.address.country = customer.address.country.toUpperCase();
  }

  return ud;
}

GDPR / consent

The agency configures Google Consent Mode v2 in GTM. You don't have to filter events by consent state — always push.

GTM will block PII forwarding to Meta/Google when the user denied ad_user_data or ad_storage. CAPI falls back to Meta's modeled signal.

⚠️ The CMP must load before GTM and call gtag('consent', 'default', {...}) early. Coordinate the injection order with the agency.