Google Ads
What is a transaction ID and why does Google Ads need it?
A transaction ID is a unique identifier for the purchase. In ecommerce, it is commonly based on the order or transaction reference. Its most important tracking role is helping systems recognize that the same order should not be counted repeatedly.
Example
A customer completes Order #1234 and refreshes the confirmation page. If the purchase tag fires again without a stable transaction identifier, Google may have difficulty distinguishing the repeat signal from a second purchase.
With a consistent transaction ID, the platform can use its current duplicate-handling logic more effectively.
It also helps debugging
When Google reports an unexpected conversion, a transaction/order reference can help you reconcile the event with Shopify rather than comparing only daily totals.
The ID should be stable and unique
Do not generate a random new ID every time the tag fires for the same order. That defeats the purpose.
Privacy still matters
Use an appropriate order/transaction identifier according to platform documentation. Do not put sensitive customer information into the field.
Transaction ID is a small implementation detail with a large impact on data quality.
Stop Google Ads counting a purchase twice
If Google Ads appears to count Shopify purchases more than once, contact us. Transaction IDs are one of the first things we check.