Fix: Deprecated attribution models still attached to conversion actions

Your audit flagged at least one conversion action whose attribution model is set to First Click, Linear, Time Decay, or Position-Based. Google retired all four models in 2023 and auto-migrated active conversion actions to Data-Driven Attribution that fall — yet legacy edge cases (custom models, paused actions, API-set values, very old accounts) still surface these dropdown values in audits today. This article tells you what the flag means, why it still matters in 2026, and how to clear it in under ten minutes.

Why this matters

Google announced the deprecation of First Click, Linear, Time Decay, and Position-Based in April 2023 [2], citing adoption rates below 3% of conversions across the network. The sunset rolled out in stages: new conversion actions lost the dropdown options in May (GA4) and June (Google Ads) 2023, and the full removal — including auto-migration of existing actions — happened around mid-October 2023 [1][3]. Only Last Click and Data-Driven Attribution remain selectable in the modern UI [4].

When this rule fires in 2026, it almost always means one of three things. Either a conversion action was created via the Google Ads API with a legacy value that the UI never re-touched; or the action is paused/archived and skipped the migration sweep; or a custom (rules-based) model created before sunset is still attached and referenced by name. None of these are common, but each one creates a measurement blind spot.

The downstream cost is real. Smart Bidding uses the attribution model on each conversion action to decide how much credit a click deserves. When one action attributes the full conversion to the first click and the rest of your account uses Data-Driven, the bidder is reading inconsistent currencies — it over-credits top-funnel clicks tied to the legacy action and under-credits assisted touches everywhere else. Reporting in Tools → Measurement → Attribution also stops being apples-to-apples; comparing two conversion actions becomes meaningless if one is frozen on a model Google no longer computes consistently.

How to verify the issue

1. Open Google Ads and go to Tools → Conversions → Summary.
2. Add the Attribution model column if it is not already visible: click the column icon, then enable Attributes → Attribution model.
3. Sort or filter by Attribution model. Anything reading First Click, Linear, Time Decay, Position-Based, or a named Custom model is what the rule caught.
4. For each flagged row, click the conversion name to open the action. Note the Source (Website, App, Import, Call) and Status (Active, Inactive, Hidden). API-imported actions and Inactive actions are the most common offenders.
5. Cross-check the Google Ads API report if you suspect API stampage: pull conversion_action.attribution_model_settings.attribution_model and look for FIRST_CLICK, LINEAR, TIME_DECAY, or POSITION_BASED enum values.

If you find zero flagged rows in the UI but the audit still surfaces the issue, the legacy value is almost certainly sitting on an archived or hidden action — toggle the Show inactive filter to make it visible.

How to fix it

Plan ten minutes per affected action; most accounts have one to three.

1. From Tools → Conversions → Summary, click the flagged conversion action.
2. Click Edit settings.
3. Under Attribution model, choose Data-driven if the action has ≥300 ad-interactions and ≥3,000 conversions in the last 30 days (Google's DDA eligibility floor [4]). For lower-volume actions, choose Last click. Do not pick a "matching" legacy model — those options no longer exist in the dropdown.
4. Click Save. The change takes effect immediately for new conversions; historical reporting is unaffected.
5. Repeat for each flagged action.
6. For any flagged action that is Inactive / Archived / Hidden and no longer used, archive it cleanly: open the action, click Remove, and confirm. This stops it from polluting future audits.
7. If you have any Custom attribution model still attached: open the model in Tools → Measurement → Attribution → Models, switch every conversion action that references it to Data-Driven or Last Click, then delete the custom model.
8. If you manage the account through the API: update conversion_action.attribution_model_settings.attribution_model to DATA_DRIVEN or LAST_CLICK for each affected action and re-deploy.

Once saved, the related concept article on data-driven attribution covers what Smart Bidding will start doing with the new signal.

How to confirm the fix worked

• Reload Tools → Conversions → Summary and confirm every active row shows Data-driven or Last click in the Attribution model column. No First Click / Linear / Time Decay / Position-Based / Custom values remain.
• Re-run the Whitead audit. The deprecated_attribution_models finding should clear.
• In Tools → Measurement → Attribution → Model comparison, the comparator should now offer only Data-Driven and Last Click as options — confirming the account is fully on the supported set.
• Give Smart Bidding 14 days before re-evaluating CPA / ROAS deltas. Bid strategies need roughly two weeks to re-learn against the corrected signal, so judge the change after the next full conversion cycle, not the next day.

This rule is upstream of almost every Smart Bidding diagnostic in the audit. When deprecated or inconsistent attribution sits on even one active conversion action, downstream findings — bid strategy underperformance, inconsistent CPA across campaigns sharing the same goal, Performance Max efficiency drift — get noisier because the bidder is averaging across mismatched credit logic. Clearing this finding first usually quiets two or three other findings on the next audit run, especially dda_consistency_across_conversions (which assumes you've already cleared legacy state) and any "bid strategy still learning past 14 days" callouts.

Related rules + concepts

• Data-Driven Attribution — the model Google migrates everything to by default, and what your account should be on for primary actions.
• Last Click to DDA migration — playbook for moving low-volume actions up once they clear the eligibility floor.
• Fix: Last Click attribution still in use — the next finding to look at if you defaulted any actions to Last Click during this cleanup.
• Conversion tracking foundations — verify the underlying action is firing correctly before worrying about which model it uses.

Sources

1. Google Ads Help — About attribution models. https://support.google.com/google-ads/answer/6259715 (accessed 2026-05-25)
2. Google Ads Developer Blog — First click, linear, time decay, and position-based attribution models are going away in Google Ads API. https://ads-developers.googleblog.com/2023/04/first-click-linear-time-decay-and.html (2023-04-20)
3. Search Engine Land — Google confirms sunset details for 4 attribution models in Ads and Analytics. https://searchengineland.com/google-confirms-sunset-details-for-4-attribution-models-in-ads-and-analytics-433352 (2023)
4. Search Engine Land — Google to sunset 4 attribution models in Ads and Analytics. https://searchengineland.com/google-sunsets-attribution-models-395297 (2023-04-06)
5. Search Engine Journal — Google Is Removing 4 Attribution Models For Advertisers. https://www.searchenginejournal.com/google-is-removing-4-attribution-models-for-advertisers/484264/ (2023)