# How long is a California smog certificate valid?

A passing California smog certificate is valid for 90 days. Get the test within 90 days before you renew the registration or hand the car to a buyer. The station sends the result to the DMV electronically, so there is nothing to mail.

## Key facts

- California smog certificates are valid for 90 days from the test date.
- When a car is sold, the seller must provide a valid smog certificate (with some exceptions for newer cars and family transfers).
- The certificate is filed electronically with the DMV by the station.

## Timing it right

| Situation | When to test |
| --- | --- |
| Registration renewal | As soon as the DMV notice arrives, so there is time for repairs if the car fails |
| Selling the car | Within 90 days before the sale ([seller rules](https://appointauto.com/guides/smog-check-when-selling-a-car-california/)) |
| Bringing a car from another state | Before you register it in California ([new residents](https://appointauto.com/guides/register-out-of-state-car-california-smog/)) |

## Next step

[Find a smog check station](https://appointauto.com/ca/) · [Smog check when selling a car](https://appointauto.com/guides/smog-check-when-selling-a-car-california/)

Official sources: [dmv.ca.gov](https://www.dmv.ca.gov/), [bar.ca.gov](https://www.bar.ca.gov/).

## Related questions

- [Where can I get a smog check near me?](https://appointauto.com/answers/where-to-get-a-smog-check-near-me/)
- [How long does a smog check take?](https://appointauto.com/answers/how-long-does-a-smog-check-take/)
- [Do I need an appointment for a smog check, and are stations open on weekends?](https://appointauto.com/answers/smog-check-walk-in-or-appointment/)
- [Can I get a smog check if my registration is expired?](https://appointauto.com/answers/smog-check-with-expired-registration/)

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Source: https://appointauto.com/answers/how-long-is-a-smog-certificate-valid/ · Last updated 2026-10-26. Station details are compiled from public listings and can change; call the shop to confirm hours and prices before you go.