Smog check frequency depends on your state, vehicle age, and whether you're buying or renewing registration

Most states that require smog checks demand one every two years for vehicles model year 1976 and newer. California, which runs the strictest program, requires checks every two years for most vehicles, but every year for vehicles model year 2000 and older in some counties. A few states—including Nevada and New Mexico—require checks only every other year or only when you transfer ownership. The exact schedule depends on where you live and what your state's air quality rules are.

If you're buying a used vehicle, you'll need a smog check before the sale closes in most states that have the requirement. This is separate from your regular renewal cycle. Some states let you skip a check in the year you buy the car, while others require it regardless. When you renew your vehicle registration, your state's DMV will tell you whether a current smog check is needed—you cannot renew without one if your state requires it that year.

Key Takeaways

  • Most states require a smog check every two years; California and a few others require annual checks for older vehicles.
  • You must get a smog check before buying a used vehicle in states with emissions testing, even if your regular renewal cycle doesn't require one that year.
  • Your state's DMV will not issue a registration renewal without proof of a current smog check if one is due.
  • Smog check validity periods vary by state—typically 30 to 90 days—so timing your test close to your registration renewal date matters.

State-by-state smog check schedules

California requires smog checks every two years for vehicles model year 2000 and newer, and every year for model year 1999 and older. Vehicles model year 1975 and older are exempt. If you live in a California county with poor air quality, the rules may be stricter. You can check your county's specific requirements through the California Bureau of Automotive Repair website.

New York requires a smog check (called an Inspection and Maintenance test) every two years for most vehicles, with some exemptions for very new cars. Texas requires checks every two years for vehicles in certain urban areas; rural areas have no requirement. Colorado, Connecticut, Delaware, Georgia, Illinois, Indiana, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Minnesota, Missouri, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, Ohio, Pennsylvania, Rhode Island, Tennessee, Utah, Vermont, Virginia, Washington, and West Virginia all have their own schedules, ranging from every two years to no requirement at all.

If you're unsure whether your state requires smog checks, contact your state's DMV or environmental agency. Many states post their requirements online, and your registration renewal notice will tell you if a test is due.

What happens if you miss a smog check important date

If your smog check is overdue when you try to renew your registration, the DMV will not issue a new registration sticker or plates. You cannot legally drive the vehicle with an expired registration, even if you've paid the registration fee. You must get a smog check first, then submit proof to the DMV before your registration becomes valid.

Some states allow a grace period of a few weeks or months after your registration expires, but this varies. Do not assume you have extra time—check your state's rules. If you're caught driving with an expired registration due to a failed smog check, you may face a fine in addition to the cost of repairs and the smog test itself.

Smog check validity and timing

A smog check certificate is valid for a limited time—typically 30 to 90 days depending on your state. If your test is valid for 30 days and your registration doesn't renew for another 45 days, you'll need to test again. Plan your smog check so the certificate is still valid when you submit it to the DMV.

If you're buying a used vehicle, the smog check must be current on the day of sale in most states. The seller is responsible for providing it in some states; the buyer is responsible in others. Check your state's rules before you negotiate the purchase. A failed smog check can delay the sale, so factor in time for repairs if the vehicle doesn't pass.

Vehicles exempt from smog checks

Very new vehicles are often exempt for a set number of years—typically the first four to eight years after purchase, depending on the state. Vehicles model year 1975 and older are usually exempt in states with smog check programs. Some states exempt vehicles that have been registered out of state for a certain period, or vehicles owned by people with disabilities.

Electric vehicles and plug-in hybrids may be exempt or subject to different rules in some states. Check your state's DMV website or call to confirm whether your vehicle type qualifies for an exemption. An exemption does not mean you don't need to renew your registration—it only means you don't need a smog check to do so.

How to find a smog check station

Your state's DMV or environmental agency maintains a list of certified smog check stations. In California, you can search the Bureau of Automotive Repair's website by zip code. In other states, the DMV website usually has a locator tool or a list of approved facilities. You can also call your local DMV office for recommendations.

Smog check costs vary by state and facility, typically ranging from $30 to $80 for a basic test. Some stations charge extra for retests if your vehicle fails. Call ahead to ask about pricing and whether you need an appointment. Many stations can perform the test while you wait, though busy locations may have a wait time of 30 minutes to an hour.

What to do if your vehicle fails a smog check

If your vehicle fails, the test facility will provide a report showing which emissions standards it did not meet. You then have a set time—usually 30 to 60 days—to repair the vehicle and retest. Some states allow you to register the vehicle conditionally while repairs are pending, but this varies. Check your state's rules before you leave the test station.

Common reasons for failure include a faulty oxygen sensor, a loose gas cap, a malfunctioning catalytic converter, or engine problems. Repairs can range from $50 for a gas cap to several hundred dollars for a converter. If repairs are expensive, get a quote from a mechanic before you commit. Some states offer repair information programs for low-income vehicle owners, though availability and funding vary.

Frequently Asked Questions

Do I need a smog check if I just bought a vehicle?

Yes, in states with smog check requirements. You must get one before the sale closes or within a set time frame after purchase. This is separate from your regular two-year renewal cycle. Check your state's rules for the exact important date.

Can I renew my registration without a smog check?

No, if your state requires one and your vehicle is due. The DMV will not issue a new registration without proof of a current smog check. If your vehicle is exempt, you can renew without one.

How long is a smog check certificate valid?

Validity periods vary by state, typically 30 to 90 days. Check your certificate or your state's DMV website for the exact period. If it expires before you submit it to the DMV, you'll need another test.

What if I move to a different state?

Your new state's smog check requirements explore once you register your vehicle there. A smog check from your previous state is not valid in your new state. You'll need to get a test that meets your new state's standards before you can register.

Can I get a smog check waiver?

Some states offer waivers for vehicles that fail repeatedly or have expensive repairs needed. may be able to access and the waiver process vary by state. Contact your state's environmental agency or DMV to learn whether a waiver is available and what you need to provide.