Ensuring GDPR Compliance with GA4: A Friendly Guide for UK Data Protection, Legal & Analytics Teams

If you had to show proof today, could you demonstrate that GA4 on your website has real consent before collection, minimal data, short retention, and a governed transfer mechanism—with evidence?

There’s been noise about “GA is illegal under GDPR,” but the past rulings targeted Universal Analytics implementations after Schrems II for unlawful EU→US transfers.

GA4 is different (no IP logging; regional controls you can switch off), and there’s no EU-wide ruling against GA4 as a product. That said, none of this replaces good governance: PECR-compliant consent, a clear lawful basis, minimisation, short retention, transparency, security, and a suitable transfer tool (e.g., DPF/UK Data Bridge or SCCs/IDTA + TRA).

As of today, there’s no EU-wide ruling that GA4 is unlawful as a product. With the EU–US DPF and the UK–US Data Bridge available for certified organisations (and SCCs/IDTA + TRA where needed), the focus for UK teams is practical: work together to make GA4 your safest, most useful dataset.

Google Analytics 4 (GA4) can be compliant in the UK—if it’s governed properly. Compliance isn’t an IT chore; it’s a Legal/DP responsibility. Use this guide to verify what matters and keep the evidence that proves it.

1) Consent and PECR (make it easy, make it real)

What to do together

• Ensure the CMP truly blocks GA4 until opt-in (desktop and mobile; first page view, deep links, and post-login pages).

• Keep “Decline” as easy and visible as “Accept”; avoid nudge patterns (colour contrast, button order, font weight).

• Honour withdrawal immediately (e.g., cookie settings link; no local fall-throughs in iframes, AMP, or subdomains).

Reality checks (lightweight)

• Run a monthly 10-minute spot test: record a decline journey on mobile and desktop (home → key page → back/forward → open a modal → new tab).

• Verify that no GA4 network calls or storage occur before consent; keep screen recordings.

Good evidence to file

• CMP text (versioned), screenshots, consent logs, and the latest pass/fail sheet from the reality test.

2) Minimise collection and avoid PII (collect only what you use)

What to agree

• A simple do-not-collect list: no names, emails, phone numbers, exact postcodes in events/parameters/URLs/search/forms.

• Scoped features: Ads/personalisation and granular location/device detail off by default; enable only with explicit scope + consent.

• Short retention by default (commonly 2–14 months); any extension is time-boxed with a written rationale and an owner.

PII hygiene routine

• Maintain a parameter allow-list (what’s permitted to reach GA4).

• Quarterly leak test: crawl key pages, submit safe test inputs, and inspect URL/query/parameters for PII patterns (emails, numbers that look like phone/postcode). Fix and re-test.

Good evidence to file

• The allow-list, last leak test report + fixes, retention setting screenshots, and any extension memo with an expiry date.

3) Lawful basis & documentation (align paper to reality)

What to align

• RoPA entry: purposes, categories, recipients, retention, transfers, security.

• Privacy & cookie notices: plain English; reflect purpose, choice, how to withdraw, and retention periods.

• Assessments: DPIA (if scale/combination raises risk) and TRA where transfers rely on SCCs/IDTA.

Practical extras

• A short “measurement purpose” paragraph agreed with Product (e.g., “identify content that confuses users; diagnose performance issues; evaluate feature adoption”).

• A one-page Measurement Charter (purpose, choice, minimisation, retention, transfers, evidence) shared internally.

Good evidence to file

• RoPA excerpt, current notices (PDF), and a one-pager Charter signed by the DPO/Head of Digital.

4) International transfers (simple story, clear owner)

What to decide together

• Your mechanism: UK–US Data Bridge where applicable, or SCCs/IDTA + TRA (with any supplementary measures).

• A plain-English board slide updated quarterly: what leaves the UK, why, mechanism relied on, monitoring cadence, who owns adjustments.

Operational tip

• Document trigger conditions (e.g., legal change, vendor certification status, risk reassessment outcome) and the named owner who executes any scope adjustment.

Good evidence to file

• The board slide (date-stamped), last review note, and any correspondence confirming vendor certification or TRA conclusions.

5) Evidence & accountability (lightweight, regular, shared)

Keep a simple evidence pack

• GA4 admin screenshots (retention, Signals, granular controls), CMP configuration, consent logs.

• Change control: who can alter GA4/CMP; SSO/2FA enabled; audit trail of edits.

• A “one shipped change” note each quarter: an example of a product/content improvement informed by GA4.

Quarterly review (30–45 minutes)

1. Walk a decline → browse → withdraw journey on phone + laptop (record).

2. Confirm retention and review any extensions.

3. Re-open the transfer slide and tick “still accurate”.

4. Review the latest PII leak test and fixes.

5. Capture the one shipped change example.

Top-line GA4 setup with full GDPR compliance (acceptance criteria—no wiring)

Share these outcomes with engineering and ask for demos/screenshots:

• Consent-gated: GA4 runs only after opt-in; decline/withdrawal stops it promptly across all key journeys (including AMP/iframes/subdomains).

• Scoped features: Ads/personalisation + granular location/device detail off by default; enable only with explicit scope, consent, and ticketed business case.

• No PII: Parameter allow-list in place; quarterly leak tests for URLs/search/forms; block list for risky keys.

• Short retention: Minimum workable window (e.g., 2–14 months); any extension is written, time-boxed, and has an owner + review date.

• Transfers governed: Mechanism recorded; “board slide” maintained; monitoring cadence + named owner; clearly defined trigger conditions.

• Auditability: Store screenshots of settings, consent copy, and one recent example of a change shipped from GA4 insight.

Common scenarios (how teams handle them well)

• A/B testing tools: Treat as separate from baseline analytics. Use consent that clearly explains experimentation; time-box data; keep experiment IDs out of PII risk.

• Server-side events / Measurement Protocol: Keep EU endpoints/processing where possible; align server logs with retention; document how consent state is respected back-end.

• App + web hybrids: Ensure the consent concept matches across app/web; avoid cross-context IDs unless there’s explicit consent and a clear purpose.

• B2B sites with forms: Watch for email/postcode leaks in query strings and page titles; strip or hash at source; test “mailto:” and CRM hand-off journeys.

Friendly FAQs (quick answers Legal gets asked)

• Do we always need consent for GA4?: If it relies on cookies/identifiers (which GA4 does): yes, under PECR. Consent first; then UK GDPR principles apply.

• Is GA4 “GDPR-illegal”?: No blanket ban. Past rulings targeted UA implementations and transfers. GA4 differs, but you still need consent, minimisation, retention, and a valid transfer tool.

• What retention is “right”?: Pick the shortest workable (commonly 2–14 months) and review. Longer windows need a written, time-boxed rationale.

• What’s the quickest win?: A Consent Reality check (10 minutes, two recordings) and a parameter allow-list. Those two shrink risk immediately.

Conclusion

GDPR compliance with GA4 doesn’t need to be heavy or adversarial. With a supportive, shared routine—real consent, minimal data, short retention, clear transfers, and light but credible evidence—you turn GA4 into the dataset you can point to with confidence. It keeps users respected, Legal comfortable, and product teams empowered to act.

Need help making GA4 compliant (and genuinely useful)?

Most analytics agencies are brilliant at tagging and dashboards—but few have deep experience in UK PECR/UK GDPR, transfers, RoPA/DPIA/TRA, or consent reality testing. That gap is why compliant setups drift.

I specialise in GA4 Legal Compliance for UK organisations. If you want GA4 to be the dataset you can proudly show to boards, auditors, and customers, I can help.

What you’ll get from my GA4 Legal Compliance Audit

• Consent Reality Film (screen recordings on real devices; pass/fail grid).

• Purpose → Metric Map (which metrics drive decisions, with named owners).

• Retention Rationale (short-by-default settings; time-boxed exceptions).

• PII Leak Report (where identifiers can enter URLs/search/forms—and the fixes).

• Transfer Slide (mechanism, monitoring cadence, and a named trigger owner).

• 90-Day Action Plan: Do now / Fix this quarter / Trial once—with owners.

If your team would benefit from an expert partner who understands both analytics and legal compliance, let’s talk.

→ Book a GA4 + GTM Audit→ Ask for sample deliverables and a short scoping call

(No jargon. No theatre. Just a clean, defensible GA4 you can rely on.)