Last Updated: October 2026
Quick Answer: The New Car Seat Side-Impact Rule
- Starting December 5, 2026, newly manufactured car seats in the U.S. must pass a federal side-impact test (FMVSS 213a).
- The test simulates a 30 mph side crash and applies to seats used by children up to 40 lbs.
- The rule is not retroactive. A seat you already own stays legal to use as long as it is not expired or damaged.
- You do not need to replace a car seat just because of this rule.
- Shopping now? Check the label or manual for FMVSS 213a, or ask our team which models already meet it.
If you have been shopping for a car seat this fall, you have probably seen the words "side impact" and "FMVSS 213a" popping up on boxes, product pages and parenting forums. That is because the United States is about to add something that, surprisingly, was never part of federal car seat testing before: a required side-impact crash test.
The new rule is good news for families, but it also raises fair questions. Is my current seat still safe? Should I wait until December to buy? How do I know if a seat already meets the new standard? This guide answers all of it in plain language, so you can make a calm, informed choice instead of a rushed one.
What Is FMVSS 213a?
FMVSS stands for Federal Motor Vehicle Safety Standard. Standard 213 is the rule that every child car seat sold in the U.S. has to meet, and for decades it focused on frontal crashes. FMVSS 213a is an amendment that adds a dynamic side-impact test for the first time.
The test places the car seat on a sled that simulates a T-bone collision, where one vehicle traveling at about 30 mph strikes the side of another. Engineers then measure how well the seat contains the child dummy and how much force reaches the head and chest. Side crashes are especially hard on young passengers because there is very little vehicle structure between the child and the point of impact, which is exactly why regulators made this a priority.
The requirement covers seats used by children who weigh up to 40 pounds, which is the stage when kids are most often riding in infant seats and harnessed convertible seats.
When Does the New Rule Start?
Car seats manufactured on or after December 5, 2026 must comply. The original deadline was June 30, 2025, but federal regulators extended it to give manufacturers more time to redesign and test their seats without creating a shortage on store shelves.
Two details are easy to miss:
- The date applies to manufacturing, not to your purchase. A seat built before December 5 can still be sold afterward, and it remains legal to use.
- Many brands are ahead of the deadline. Some models on the market today are already certified to the new standard. On the Nuna RAVA next and the Nuna REVV maxx, for example, Nuna lists certification to both FMVSS 213a and 213b.
Do I Need to Replace My Current Car Seat?
No. This is the single most important point in this whole article. The new standard is not retroactive, and federal safety officials are not recommending that families throw out seats that met the rules when they were made. There is no recall tied to this change.
A seat you already own is the right seat to keep using as long as all of the following are true:
- It has not reached its expiration date (printed on a label or molded into the shell).
- It has not been in a moderate or severe crash.
- Your child is still within its height and weight limits.
- It is installed tightly and the harness fits snugly every ride.
Correct installation and a snug harness still matter more than any new label. A brand-new seat that is installed loosely will not protect a child as well as an older, compliant seat that is installed correctly.
What Changes for Parents Shopping Right Now
If you are expecting a baby or your child is about to move to the next seat, the new rule gives you one more thing to look for, not a reason to panic. Here is how it plays out in practice.
Look for the label or the manual
Manufacturers are adding FMVSS 213a language to labels, manuals and product descriptions. Not every box will mention it yet, so if you cannot find it, ask the brand or ask us. Our team can check the specifications of any seat in the store before you buy.
Expect some design updates
To pass the new test, many seats are getting deeper side wings, more energy-absorbing foam around the head and extra structure along the shell. Some seats may feel a bit wider than older versions, so measuring your back seat is still a smart step, especially if you need to fit two or three seats across.
Weight ranges may shift
The side-impact test arrives together with a broader update to Standard 213. Labels now have to state the maximum height and weight for each mode a seat can be used in, and booster seats have to be labeled for children who weigh at least 40 pounds. Always follow the limits printed on your specific seat.
What about FMVSS 213b?
You may also see FMVSS 213b on labels. It becomes mandatory on the same date, December 5, 2026, and it updates the test bench used for frontal crash testing so it better represents the rear seat of a modern vehicle. When a brand lists both 213a and 213b, the seat already meets the side-impact test and the updated frontal test.
Car Seats That Already List FMVSS 213a
You do not have to wait until December to buy a seat built for the new standard. These are examples we carry where the brand already lists side-impact certification or dedicated side-impact technology. Availability of each color changes often, so use the links to see what is in stock.
| Car Seat | Type | Rear-Facing Range | What the Brand Highlights |
|---|---|---|---|
| Nuna RAVA next | Convertible | 5 to 50 lbs | Certified to FMVSS 213a and 213b, slim fit for 3 across |
| Nuna REVV maxx | Rotating convertible | 5 to 40 lbs | Certified to FMVSS 213a and 213b, one-hand 360° rotation |
| Cybex Aton G2 Swivel | Infant seat | Infant stage | Linear Side-Impact Protection, load leg, 180° swivel base |
Nuna RAVA next
For families who want one seat from the hospital ride home through the toddler years, the RAVA next is a strong place to start. It rides rear-facing up to 50 pounds, which lets kids stay in the safer rear-facing position for longer, then forward-facing with the harness up to 65 pounds. Nuna designed it slim enough to fit three across in many mid-size vehicles, and its tension doors make a tight installation easier to achieve.
Nuna REVV maxx
If loading a toddler into the back seat is starting to hurt your back, a rotating seat can make a real difference. The REVV maxx turns toward the door with one hand, then locks back into its riding position. It is rated rear-facing from 5 to 40 pounds and forward-facing up to 65 pounds. For a broader look at swivel seats, see our guide to rotating car seats in 2026.
Cybex Aton G2 Swivel
For the newborn months, the Aton G2 Swivel pairs a 180° rotating base with an anti-rebound load leg and what Cybex calls Linear Side-Impact Protection. The carrier still clicks off the base and onto compatible strollers, so you keep the convenience of an infant seat.
What About Booster Seats?
The side-impact requirement targets seats for children up to 40 pounds, so it mainly affects infant seats and harnessed seats. Boosters are still covered by the rest of the federal standard. Seats like the Nuna AACE 2-in-1 booster, which starts as a high-back booster at 40 pounds and at least 4 years old, already follow the 40-pound booster minimum. You can compare more options in our booster car seat collection.
A Simple Checklist Before You Buy
- Confirm your child's current height and weight, then pick the stage that fits: infant, convertible or booster.
- Look for FMVSS 213a on the label, manual or product page, or ask our team to check.
- Measure your back seat and confirm the seat fits your vehicle.
- Register the seat with the manufacturer so you hear about recalls.
- Write down the expiration date and keep the manual in the car.
- Practice the installation and the harness pinch test before your first ride.
Small extras help too. A rear-facing mirror such as the Primo Passi baby car mirror lets the driver glance at a rear-facing baby without turning around. Choose one that attaches securely to the headrest and does not touch the car seat itself.
Frequently Asked Questions
When does the new car seat side-impact rule take effect?
The FMVSS 213a requirement applies to car seats manufactured on or after December 5, 2026. Seats made before that date can still be sold and used.
Do I have to buy a new car seat because of FMVSS 213a?
No. The rule is not retroactive and there is no recall. Keep using your current seat as long as it is not expired, has not been in a significant crash and still fits your child.
How can I tell if a car seat meets FMVSS 213a?
Check the labels on the seat, the manual or the product page. Not every brand prints it on the box yet, so you can also contact the manufacturer or ask our team at MacroBaby to verify a specific model.
What does the side-impact test simulate?
It simulates a T-bone crash in which a vehicle traveling at about 30 mph strikes the side of the car where the child is riding, and it measures how well the seat protects the child's head and body.
Does FMVSS 213a apply to booster seats?
The side-impact test applies to seats used by children up to 40 pounds, so it mainly affects infant seats and harnessed seats. Boosters must still meet the rest of the federal car seat standard.
Should I wait until after December 5 to buy a car seat?
There is no need to wait. Several seats already list FMVSS 213a certification, and any seat that meets current federal standards and is installed correctly protects your child. Choose the seat that fits your child, your car and your routine.
Shop With Confidence at MacroBaby
MacroBaby is one of the largest baby stores in the United States, with a physical store in Orlando and a full online store. Our team helps families in English, Portuguese and Spanish on every channel, and we are happy to check whether a specific seat already meets FMVSS 213a before you buy. Browse our full car seat collection or visit us in Orlando to see the seats in person.
