# How to find ad sets bidding against each other

> Tier: deep. Full contract: quantified decision rules and evidence requirements.
> Contract v1.0.0 · last verified 2026-08-29 · status: reviewed.

Where your own ad sets compete for the same people on Meta and TikTok, measured with the platforms' own overlap data, and what to merge or exclude.

**Intent.** Stop paying auction premiums against yourself, with the overlapping pairs named and sized.

## When to use

- CPMs creeping while reach stalls.
- After audience proliferation: many lookalikes and interest stacks built over months.
- Before consolidating an account structure.

## When not to use

- Accounts with one or two audiences: nothing to overlap.
- Broad or Advantage+ targeting everywhere: overlap is delegated to the platform there, and the finding would be decorative.

## Sources

Required: Meta Ads
Optional: TikTok Ads

## Preconditions

- Audiences and ad sets readable on the ticked accounts.
- Spend history to weight the findings.

## Inputs

- `scope`: Campaigns whose audiences to cross. Default: active prospecting.

## Procedure

1. List audiences and their definitions on Meta. — tools: `meta_get_audiences`, `meta_get_audience_details`
2. On TikTok, run the platform's own overlap measurement across the active audiences. — tools: `tiktok_get_audience_overlap`, `tiktok_get_audiences`
3. Map which ad sets use which audiences, with spend. — tools: `meta_get_adsets`, `meta_get_insights`, `tiktok_get_adgroups`
4. Rank overlapping pairs by combined spend and overlap share.

## Decision rules

- **When** Two ad sets with meaningful spend target audiences overlapping above 40% → **conclude** Consolidation candidate: merge, or exclude one from the other; show both options with their trade-offs.
- **When** Overlap is high but one ad set is remarketing and the other prospecting → **conclude** Fix is exclusion, not merging: remarketing pools must be excluded from prospecting, and the absence of that exclusion is the finding.
- **When** Overlap exists but combined spend is marginal → **conclude** Note and skip: auction self-competition only costs money where money is.

## Evidence requirements

- Every pair carries the overlap measurement, both spends, and the audience definitions.
- TikTok findings quote the platform's own overlap tool, not an inference.

## Human approval boundary

- Merging audiences and adding exclusions are edits humans apply; status changes proposed here go through Safe Writes.

## Failure modes

- Meta does not expose pairwise overlap percentages for every audience type via API; where measurement is unavailable, the skill says inferred-from-definitions and lowers confidence.
- Lookalikes of the same seed at different percentages nest by construction: 1% inside 5%. That is expected, and only a finding when both run prospecting simultaneously.
- Auction overlap is also time-dependent: dayparting can make overlapping audiences never actually meet.

## Output

- **Pairs, ranked**: Overlap, spends, definitions, proposed fix per pair.
- **Missing exclusions**: Prospecting ad sets without remarketing exclusions.
- **Structure proposal**: The consolidated target structure, if warranted.

## Related

- Skill: [meta-delivery-diagnosis](https://www.getmcpads.com/skills/meta-delivery-diagnosis.md)
- Skill: [account-audit](https://www.getmcpads.com/skills/account-audit.md)
- Guide: [campaign-audit](https://www.getmcpads.com/guides/campaign-audit.md)