The short answer
A zero-dollar authorization (often called "$0 auth" or "zero-auth") is a request sent to the card issuer asking "is this card valid, is the CVV correct, does AVS match?" without reserving any funds on the cardholder's account. The response is approve or decline — same as a regular auth — but no hold is placed, no funds move, and the card statement shows nothing. Perfect for verifying cards before storing them or billing later.
How it differs from a $1 pre-auth
- $1 pre-auth: Reserves $1 on the card (held until released). Appears on pending transactions for 1-7 days. Shows up in the cardholder's app. Generates support calls from confused customers.
- $0 auth: Reserves nothing. Invisible to the cardholder. No pending transaction, no support calls.
- AVS/CVV verification is equivalent for both — issuer returns match/mismatch the same way.
The reason operators historically used $1 pre-auths instead of $0 auths: not every issuer supported $0 auth reliably. As of 2023-2026, support is ~95%+ across U.S. issuers and 85%+ internationally. $1 pre-auths are a legacy pattern worth retiring.
When operators use $0 auths
- New account signup. Customer saves a card for future subscription; run a $0 auth to verify the card is real and issuer-approved before storing.
- Stored-credential refresh. Before running a subscription charge, send a $0 auth to check the card's still valid. If declined, trigger account updater flow.
- Card-on-file consent verification. Pair the $0 auth with the COF initial-storage flag so subsequent MITs have a clean origin story.
- Two-step checkout. Customer configures their subscription plan, card is validated via $0 auth, first charge fires when they confirm.
- Wallet verification. Adding a card to Apple Pay / Google Pay relies on $0 auths to verify eligibility.
What operators need to know
- Treat $0 auth results as signal, not proof. Approve means the card is in good standing this second, not that a future real charge will approve. Approval rates on the real charge are ~90% of the $0 auth approval rate, depending on vertical.
- $0 auths count against some issuer velocity limits. Excessive $0 auths on the same card within a short window can trigger issuer-side block. Don't auth the same card 10 times in 10 minutes.
- Gateway support varies. Check your gateway's $0 auth support — Stripe, Adyen, Braintree, Worldpay all support. Some legacy ISO gateways don't expose it in the UI but do support via API.
- Not for transaction verification. A $0 auth does NOT reserve funds. If you need to ensure $200 is available before you start service, that's a $200 pre-auth followed by delayed capture — not a $0 auth.
- Some issuers respond differently. A minority of issuers return "approved" for all $0 auths regardless of validity, making them less useful. Track approval rates per issuer and discount low-signal issuers in your fraud scoring.
- Audit log everything. $0 auths should be logged like real transactions — fraud teams use $0-auth decline patterns to detect card testing.