When Is a Smog Check Required in California? Official Registration & Timing Rules
California's official smog timing rules — biennial renewal, vehicle sales, out-of-state moves, and the 90-day certificate window — from DMV registration requirements and BAR certificate rules.
Quick read: Most California vehicles need a smog check every two years at registration renewal, and again when sold or transferred (if the vehicle is more than 4 years old). New residents must smog within 20 days of moving in. Your DMV renewal notice is the official word on whether your car needs one this cycle.
1. Biennial registration renewal
The standard cycle is every other year. Your DMV renewal notice — which arrives about 60 days before your registration expires — states whether a smog certificate is required for that renewal. New gasoline vehicles are exempt for their first 8 model years (an abatement fee applies instead). If the DMV's profile flags your vehicle, the notice may direct you to a STAR-certified station specifically. What STAR certification means →
2. Selling or transferring a vehicle
When a vehicle is sold, the seller is generally responsible for providing a valid smog certificate if the vehicle is more than 4 years old. The certificate must be dated within 90 days of the sale. Family transfers (e.g., parent to child) are exempt, as are vehicles 4 model years old or newer (the buyer pays a smog transfer fee at the DMV instead).
3. Moving to California
New residents must register an out-of-state vehicle within 20 days of establishing residency, and a California smog inspection is required at that first registration. An out-of-state smog certificate is not accepted. Full new-resident process →
4. The 90-day certificate window
A California smog certificate is valid for 90 days from the inspection date for registration purposes. You can test as early as 90 days before your registration is due — there's no advantage to going earlier, and after 90 days a new inspection is required. The result transmits to the DMV electronically, so you can usually pay your registration online the same day. How certificate filing works →
Timing cheat-sheet
- Renewal: every 2 years, per your DMV notice (arrives ~60 days early)
- Sale/transfer: seller provides cert if vehicle >4 years old, within 90 days
- New resident: CA smog within 20 days of moving
- Certificate validity: 90 days; test up to 90 days before due
Walk in any day — most checks take about 15 minutes, and we file your result with the DMV the same business day. Find your location →
Sources: California DMV registration rules (dmv.ca.gov), BAR certificate validity rules (bar.ca.gov). Your DMV renewal notice governs your specific vehicle.
Need a smog check? Text (760) 825-SMOG for $10 off your first visit at any of our 15 STAR-certified locations.