Tracking Affiliate Conversions in Google Ads with Offline Conversion Upload

When your conversion happens on a merchant's site, Google's tag can't fire. The replacement is Offline Conversion Imports (OCI) — you upload conversions to Google with the original gclid, and Google credits the right ad and keyword.

What you need

• A Google Ads account with conversion tracking enabled.
• A conversion action of type Import — Other data sources.
• The original gclid, captured on landing and stored as a SubID in your affiliate link.
• An OAuth-enabled service account that can call the Google Ads API.

The OCI payload

{
  "operations": [{
    "create": {
      "gclid": "Cj0K...XYZ",
      "conversionAction": "customers/123/conversionActions/456",
      "conversionDateTime": "2026-06-07 12:34:56+00:00",
      "conversionValue": 49.0,
      "currencyCode": "USD",
      "orderId": "ORDER-12345"
    }
  }]
}

From postback to upload

1. Affiliate postback arrives with gclid in SubID and a payout.
2. Your endpoint enqueues a conversion-upload job.
3. A worker batches conversions and posts to googleads.googleapis.com.
4. Google ingests within a few hours — Smart Bidding uses the new signal.

Latency rules

• Conversions must be uploaded within 90 days of the click. Earlier is better — Smart Bidding ignores stale signals.
• Re-uploading the same orderId is fine; Google deduplicates.

Verifying it works

In Google Ads → Tools → Conversions, open your conversion action and check the Diagnostics tab. After ~24h you'll see imported count, match rate, and any rejected rows.

Common errors

• UNPARSEABLE_GCLID: the gclid got truncated or mangled — usually missing URL encoding.
• CONVERSION_PRECEDES_CLICK: timestamps are off; check timezones.
• EXPIRED_GCLID: the click is older than the conversion window of the action.