IAB Transparency & Consent Framework (TCF) — What It Is and How to Check

Updated August 2026 — If your website serves programmatic advertising to EU users, you have likely encountered the IAB TCF. This guide explains what it is, who needs it, and how to verify your implementation with a free scan.

What is the IAB TCF?

The IAB Transparency & Consent Framework (TCF) is an industry standard developed by IAB Europe that enables digital advertising companies to collect and process personal data in compliance with the GDPR and ePrivacy Directive. It provides a standardised way for publishers, advertisers, and ad-tech vendors to manage user consent across the programmatic advertising supply chain.

TCF is currently in its second major version (TCF v2), which was introduced in 2019 and became mandatory for IAB Europe members in August 2020. A v3 update is under development as of 2026.

How it works:

1. A user visits a website that uses a Consent Management Platform (CMP) implementing TCF.
2. The CMP presents a consent dialog with vendor-specific and purpose-specific options.
3. The user's choices are encoded into a TC string (Transparency & Consent string) — a base64-encoded string stored in a first-party cookie or local storage.
4. Ad-tech vendors in the programmatic chain read the TC string to determine which purposes and vendors the user has consented to.
5. The __tcfapi JavaScript API allows vendors and CMPs to communicate consent status in real time.

Who needs TCF?

TCF is relevant for any organisation that participates in programmatic advertising with EU users:

• Publishers who sell ad inventory through ad exchanges or SSPs
• Advertisers using programmatic buying or retargeting in the EEA
• Ad-tech companies — DSPs, SSPs, DMPs, analytics providers
• Any website using Google Ad Manager, Google Ads, or other ad platforms that require TCF signals

Google has integrated TCF into its ad platforms, requiring publishers using Google Ad Manager or AdSense for EU traffic to register with a TCF-compliant CMP.

TCF vs Google Consent Mode v2

These two frameworks serve different but complementary purposes:

Aspect	IAB TCF	Google Consent Mode v2
Scope	Programmatic advertising supply chain	Google tags (Ads, Analytics, Floodlight)
Standard body	IAB Europe	Google (proprietary)
Signal format	TC string (base64 encoded)	gtag/datalayer consent defaults and updates
Required since	2020 (IAB) / 2024 (Google integration)	March 2024 (Google requirement)
Best practice	Use a CMP that supports both TCF and Google Consent Mode v2

A single CMP can implement both frameworks simultaneously. When a user sets their consent preferences, the CMP writes both the TCF TC string and the Google Consent Mode defaults — covering the entire ad-tech ecosystem.

How to check if a site uses TCF

1. Browser console: Open DevTools and type typeof __tcfapi. If it returns "function", TCF is active.
2. Check cookies: Look for cookies starting with IABTCF_ (e.g. IABTCF_TCString, IABTCF_VendorConsents).
3. Use our free scanner: Enter any URL below and see the "IAB TCF" check result instantly.

Common TCF issues

• Missing __tcfapi: The TCF API is not available on the page — vendors cannot read consent signals.
• Partial implementation: TCF cookies exist but the API is missing, or vice versa. This can cause inconsistent consent signalling.
• TCF present but no Google Consent Mode v2: Your CMP may handle programmatic consent but leave Google tags without the required Consent Mode defaults.
• Full TCF + Consent Mode v2: Both frameworks detected — CMP is covering the full advertising ecosystem.

Free TCF Compliance Check

Run our free scanner on any URL to check for IAB TCF, Google Consent Mode v2, cookie consent platforms, and 6 other compliance checks. It works on any website — WordPress, Shopify, Webflow, Next.js, or hand-written HTML.

Run free scan →

Disclaimer: Automated technical checks only — not legal advice. Full compliance review requires a qualified professional.