Guide Updated 2026-10-30
Smog check when buying or selling a car
The seller must give the buyer a passing smog certificate, and on a private sale it must be less than 90 days old, unless the car is a gas vehicle four model years old or newer or the sale is between close family.
The short answer
If you sell a covered car in California, you give the buyer a passing smog certificate. The seller supplies it. For a private sale the test has to be less than 90 days old. For a dealer sale the certificate is good for two years. A few sales skip the check, including gas cars that are four model years old or newer and many family transfers.
Plan the timing. Test close to the sale, not months ahead. A pass counts for 90 days on a private sale. If the buyer is slow and day 91 arrives, you test again.
This guide covers the whole chain. It starts with the seller side, then the buyer side, then dealers, family transfers, diesels, and what to do if the car fails.
Who has to get the smog check when a car is sold
The seller. Both DMV and BAR say a seller must provide a valid smog certification when a covered car changes hands. The buyer does not have to arrange the test. The buyer does need to confirm that the certificate exists and is still good.
The check applies in every county, not only in biennial ones. If a covered car is sold in a rural county that has no biennial program, the sale still needs a certificate. The car also needs to be in an age group that is not exempt. A gas car that is four model years old or newer is exempt, and the buyer pays an $8 smog transfer fee to DMV instead.
The test results go to DMV electronically. You do not have to carry a paper certificate to DMV. Keep a copy of the vehicle inspection report anyway so the buyer can see it.
How long a smog check is good for
The answer depends on who is selling. Here are the rules from the Health and Safety Code.
| Who the certificate is for | How long it counts | Where the rule comes from |
|---|---|---|
| Private party sale | 90 days from the test | Health and Safety Code 44015(e) |
| Dealer sale | Two years, or until the car is sold and registered, whichever is first | Health and Safety Code 44015(f) |
| Renewal test before it is due | Test any time in the 90 days before the due date | Health and Safety Code 44015(g) |
| Biennial check right after a sale | A certificate from the last six months covers it | Health and Safety Code 44011(a)(2) |
For a private sale, ninety days is the number to remember. Count from the day of the test. A smog certificate does not renew itself, and a long listing time can use up the window. If you list a car in January and the deal closes in May, you need a fresh test.
Dealer sales
Dealers carry the smog duty, not the buyer. A dealer certificate is valid for two years or until the car is sold and registered, whichever comes first. BAR says a dealer car must have passed a smog check within the past two years. If you buy from a dealer, ask to see the certificate. If the dealer cannot show one, ask why before you sign.
Step by step for sellers
- Check the model year and fuel. Gas and hybrid cars 1976 and newer are covered. Diesels 1998 and newer under 14,000 pounds are covered. Electric cars and 1975 and older cars are not.
- Count the age. If the gas car is four model years old or newer, you are exempt. The buyer pays $8 at DMV.
- Test within 90 days of the sale. Do it once you have a real buyer or an offer in hand. Pretests are allowed, but the pretest is not the certificate.
- Keep the report. The station sends the result to DMV. You can look up any car at bar.ca.gov/inspection from midnight the day after the test.
- Report the sale to DMV within 5 days.
A typical test costs $67.20 on average. BAR reports that number as the statewide average, and stations set their own prices. On top of the test price, a passing car pays the $8.25 certificate fee. See the smog check cost guide for the breakdown.
Step by step for buyers
- Ask for the certificate. A private party seller should show you a passing report that is less than 90 days old.
- Look the car up. Enter the plate or VIN at bar.ca.gov/inspection to see the smog history. The result appears from midnight the day after the test.
- Compare the dates. Day 90 is the last day a private party certificate counts. If the paper is close to that edge, give the seller time to retest.
- Transfer within 10 days. The buyer has 10 days to transfer ownership after a private purchase.
- Keep your own copy. A certificate from the last six months also covers you if your next biennial check comes up soon after the sale.
The 90 day window in practice
| Day | What happens | Who acts |
|---|---|---|
| Day 0 | The car passes and the certificate goes to DMV electronically | Seller |
| Day 5 or sooner | Sale is reported to DMV | Seller |
| Day 10 or sooner | Ownership is transferred at DMV | Buyer |
| Day 90 | The certificate stops counting for a private sale | Both |
The sale and the transfer both run on their own clocks. The seller has 5 days to report the sale. The buyer has 10 days to transfer ownership. The certificate runs on a separate 90 day clock. As long as the transfer is filed inside the 90 days, the smog check does not need a second round.
Family transfers and other sales that skip the check
Vehicle Code section 4000.1 lists the transfers that do not need a new smog certificate. The most useful one is the family list. A transfer between a spouse, parent, grandparent, sibling, child or grandchild is exempt.
| Situation | Smog check at transfer | Notes |
|---|---|---|
| Transfer filed within 90 days of a valid smog certificate | No new check | The existing certificate covers it |
| Gas vehicle four model years old or newer | No | Buyer pays an $8 smog transfer fee to DMV |
| Transfer between spouses | No | Vehicle Code 4000.1 |
| Transfer between parent and child | No | Includes grandparent and grandchild |
| Transfer between siblings | No | Vehicle Code 4000.1 |
| Sole proprietorship transferring to the proprietor | No | Vehicle Code 4000.1 |
| Certain lessor and lessee transfers | No | Vehicle Code 4000.1 |
| An owner is added to the title | No | Vehicle Code 4000.1 |
| Model year 1975 and older gas vehicle | No | Never covered by the program |
| Diesel, model year 1998 and newer, 14,000 pounds or less | Yes | No four year pass for diesel |
| Family member bought the car for you without titling it in their name first | Yes | The family exception is lost |
The family catch. The exemption works only between the two family members on the title. If a relative buys a car and hands it to you without first putting it in their own name, DMV treats the sale as a regular sale. You then need a smog certificate.
The "owner added to title" exemption helps when a spouse or parent joins the title. It does not help when the car is being given to a stranger with a family tie on the paperwork.
Why diesels always need a smog check at sale
The four year pass for newer cars does not apply to diesel. Vehicle Code section 4000.1 carves diesel out of that exemption. BAR also says there are no model year exceptions for diesel. If you sell a 1998 or newer diesel under 14,000 pounds, you need a smog certificate no matter how new the truck is.
Heavy diesels above 14,000 pounds are not part of Smog Check. They fall under the CARB Clean Truck Check program. Check the main rules guide for the full list.
What if the car fails when you try to sell it
About 8.5 percent of initial smog checks fail, and the odds climb with age. The chart shows 2025 results for 2000 and newer cars.
Failure rate on the first test by model year, 2025
Overall, 91.1 percent of initial tests in 2025 ended in a certificate. If your car fails, you get a vehicle inspection report with the reasons. Fix the problem and retest. Some repairs may be covered by the emissions warranty, so ask a dealer first. The average reported emissions repair in 2025 was $756.68.
Sellers should know three things.
- No repair cost waiver on a sale. The waiver is not available when a car is sold.
- No state repair assistance. The Consumer Assistance Program covers cars that failed a biennial check, not a change of ownership check.
- Retirement is a possible way out. If the car failed its most recent check, the state retirement program pays $1,350 with no income test, or $2,000 if you are income eligible. The car must run on its own power and have continuous registration.
Our failed smog check guide has the full options.
Test early or test late, and where to test
A pretest is allowed. Stations must give you a written estimate before they start, and that goes for a pretest as well. A pretest shows you what would fail, and it costs less than a surprise on the day of the sale. Just remember that only a real certificate counts for the buyer, and the 90 day clock starts at the certificate.
Any licensed station can test a car for a sale, unless the car was directed to a STAR station or is a gross polluter. If your car is old, ask the shop what it will do if the car fails. Test and repair stations can fix the car on the spot. Test only stations cannot do emissions repairs.
| Station type | Certificates on the first test | Share of first tests |
|---|---|---|
| STAR Test Only | 5,822,635 | 90.9% |
| STAR Test and Repair | 2,710,210 | 90.3% |
| Non STAR Test Only | 367,923 | 93.3% |
| Non STAR Test and Repair | 1,314,958 | 93.4% |
Do not read too much into the gaps. STAR stations get the cars most likely to fail, so their pass rate looks lower. The point for sellers is simple. About nine in ten first tests end in a certificate, so most sales go smoothly.
Smog checks at sale in the country areas
BAR runs three program areas. In rural change of ownership areas, a smog check comes up only at a sale or a first registration. These areas are small. BAR logged just 69,136 initial tests there in 2025, compared with 9,710,327 in enhanced areas, or about 0.7 percent as many. The fail rate on the newer cars was 8.1 percent, close to the state figure.
If you live in a county that is not on DMV's biennial list, you will most likely meet the smog check at a sale first. Do not assume that you can skip it because your county has no renewal check. The sale rule applies everywhere in the state.
Common sale problems
- The station cannot test the car. This often happens when DMV still shows an old address or program area. Fix your address with DMV, or call the DCA Consumer Information Center at (800) 952-5210. BAR has a zip update page for this.
- The car was bought out of state. The first California registration needs its own check. See moving to California.
- The buyer wants a recent pass but the seller has an old one. After 90 days, the seller must test again.
Questions people ask
Who pays for the smog check when selling a car in California?
The seller must provide a valid smog certification at sale. The law puts the duty on the seller. Buyer and seller can agree to split the cost, but the certificate is still the seller's job.
How long is a smog check good for when selling a car?
On a private sale, a certificate is valid for 90 days. A dealer certificate is valid for two years or until the car is sold and registered, whichever comes first.
Do I need a smog check to transfer a car to a family member?
No, if the transfer is between a spouse, parent, grandparent, sibling, child or grandchild. The catch is that the relative must be on the title. A family member who bought the car for you without titling it first triggers a smog check.
Does a new car need a smog check when sold?
A gas vehicle four model years old or newer does not. The buyer pays an $8 smog transfer fee to DMV instead. Diesel vehicles get no such exemption.
Do I need a smog check to sell a diesel truck?
Yes, if it is model year 1998 or newer and weighs 14,000 pounds GVWR or less. Diesels have no four year sale exemption.
What if my car fails the smog check when I am selling it?
You need to repair it and retest to give the buyer a certificate. A repair cost waiver and state repair assistance are not available for a sale. If the car failed its latest check, you may be able to retire it through the state program for $1,350 or $2,000.
How long does the buyer have to transfer ownership?
The buyer has 10 days after a private purchase. The seller has 5 days to report the sale to DMV.
Can I check whether a car has passed smog before I buy it?
Yes. BAR lets you look up any car's smog history at bar.ca.gov/inspection. Results show from midnight the day after the test.