# Payment-ExpireAt Payment expiration time as a Unix timestamp in seconds. Must be **in the future** — a value in the past, or equal to the current second, is rejected at creation with a `400` error (`expireAt must be in the future`). There is no minimum beyond that, so short-lived payments are allowed. Defaults to 7 days after creation when omitted. Once this time passes, the payment transitions to `EXPIRED` and can no longer be confirmed; reading an overdue pending payment already reports it as `EXPIRED`. **number**number\ Payment expiration time as a Unix timestamp in seconds. Must be **in the future** — a value in the past, or equal to the current second, is rejected at creation with a `400` error (`expireAt must be in the future`). There is no minimum beyond that, so short-lived payments are allowed. Defaults to 7 days after creation when omitted. Once this time passes, the payment transitions to `EXPIRED` and can no longer be confirmed; reading an overdue pending payment already reports it as `EXPIRED`. **Example: **`1663581391` Payment-ExpireAt ``` 1663581391 ```