You can submit smog check results to the California DMV through their online portal, by mail, or in person at a DMV office

California requires smog check certificates for vehicle registration renewal in most counties. Once you pass the test at a smog station, you have two main paths: the smog station can submit the results electronically to the DMV on your behalf, or you can submit them yourself online through the DMV's website. Most smog stations now do this automatically, but if yours doesn't, or if you want to handle it yourself, the online submission takes about 10 minutes and requires your vehicle's VIN, license plate number, and the smog certificate number from your test results.

Key Takeaways

  • Many smog stations submit results to the DMV electronically at no extra cost, so check with your station before submitting yourself.
  • The DMV's online smog check submission portal is at dmv.ca.gov and requires your vehicle VIN, current license plate, and smog certificate number.
  • You need the original smog certificate or a copy with the station's stamp and signature to submit online or by mail.
  • If you submit online, the DMV typically processes the results within one to three business days.
  • You can renew your vehicle registration when ready after submitting smog results online; you do not have to wait for DMV confirmation.

Check whether your smog station already submitted the results

When you pass a smog test, ask the station directly: "Will you submit this electronically to the DMV?" Most stations in California now do this as part of the standard service, and it costs nothing extra. If they say yes, you are done — the DMV will receive the results within one to two business days, and you can proceed with registration renewal without doing anything else.

If the station says they do not submit electronically, or if you are unsure, you can check the DMV website or call the station back before leaving. Do not assume it was submitted. If results do not reach the DMV within a few days, your registration renewal will be held up.

Gather the information you need to submit online

Before you go to the DMV website, collect these items from your smog certificate:

  • Your vehicle's VIN (Vehicle Identification Number) — found on your registration or dashboard
  • Your current California license plate number
  • The smog certificate number — printed on the certificate itself, usually at the top
  • The test date
  • The smog station's name and location

The smog certificate is a physical document the station gives you when you pass. Keep it in a safe place; you may need to show it to the DMV or your insurance company later. If you lost the certificate, contact the smog station where you tested — they can print a duplicate or provide the certificate number over the phone.

Submit your smog results through the DMV website

Go to dmv.ca.gov and look for the "Submit Smog Check" or "Vehicle Registration" section. The exact link changes, but the DMV's homepage has a search bar where you can type "submit smog check online." This will take you to the official submission form.

Fill in the form with your vehicle information and the smog certificate details. The form asks for your VIN, license plate, certificate number, and the test date. Double-check each entry — a typo in your VIN or plate number will cause the submission to fail or attach to the wrong vehicle. Once you submit, the DMV sends a confirmation message to the screen; take a screenshot or note the confirmation number.

Processing usually takes one to three business days. You do not have to wait for the DMV to confirm receipt before you renew your registration online — you can proceed with registration renewal when ready after submitting smog results.

Submit by mail if you prefer not to use the website

If you do not want to submit online, you can mail your smog certificate to the DMV. Send the original certificate (or a certified copy) along with a note that includes your name, vehicle VIN, license plate number, and the certificate number. Mail it to the DMV address for your county — this is listed on the DMV website under "Office Locations."

Mail submission takes longer than online or electronic submission from the station. Allow one to two weeks for the certificate to arrive, plus another week for the DMV to process it. If you are close to your registration renewal important date, online submission is faster.

What to do if your smog results do not show up in the DMV system

If you submitted online or the station said they would submit electronically, check back after three business days. Log into your DMV account at dmv.ca.gov or call the DMV customer service line for your county. Have your VIN and license plate number ready.

Common reasons results do not appear: the certificate number was entered incorrectly, the VIN does not match the DMV's records, or the smog station has not yet sent the results. If the station submitted it, ask them to verify the submission went through. If you submitted it yourself, recheck the form for typos and resubmit if needed. The DMV will not charge you to resubmit.

Renew your registration after submitting smog results

Once you have submitted your smog results — whether online, by mail, or through the station — you can renew your vehicle registration. You do not have to wait for the DMV to send you a confirmation that they received the smog check. Go to dmv.ca.gov, log into your account, and start the registration renewal process. The system will show whether smog results are on file.

If the system says smog results are not found, wait another day or two and try again. If it still does not appear after three business days, contact the DMV or the smog station to troubleshoot. You cannot complete registration renewal without a passing smog check on file (in most California counties), so this step is important.

Frequently Asked Questions

Do I have to submit smog results myself, or does the station do it automatically?

Most stations submit results electronically to the DMV at no extra charge. Ask your station before you leave. If they do not, you can submit online yourself through dmv.ca.gov in about 10 minutes. Either way, the results reach the DMV within a few days.

What if I lost my smog certificate?

Contact the smog station where you tested and ask for a duplicate or the certificate number. Provide your name, vehicle VIN, and the approximate test date. The station can print a copy or give you the number so you can submit online. If you cannot reach the station, you may have to retake the test.

Can I renew my registration before the DMV confirms it received my smog results?

Yes. You can start your registration renewal online when ready after submitting smog results. The DMV system will show whether results are on file. If they are not yet in the system, wait a day and try again. Do not wait for a separate confirmation letter.

How long does it take for the DMV to process smog results submitted online?

Online submissions typically process within one to three business days. Electronic submissions from the smog station may be faster — sometimes within 24 hours. Mail submissions take one to two weeks. Check your DMV account after three business days to see if results appear.

What if I submit smog results but my registration renewal is still blocked?

This usually means the smog results have not reached the DMV yet, or there is a mismatch between the information on your certificate and your DMV record (like a different VIN or plate number). Wait three business days, then log into your DMV account and check again. If the problem persists, call the DMV or the smog station to verify the submission.