What to do if someone rear ends you in California The rear driver starts at fault.

Call 911, photograph both cars before anything moves, and see a doctor the same day even if nothing hurts yet. Then report the crash to your own insurer and give the other driver’s insurer nothing until you know how badly you are hurt.

Do this in the first hour

None of this is complicated, and all of it is easy to skip while your hands are shaking.

1. Check everyone, then call 911. If anyone is hurt, say so on the call. That is what brings paramedics and creates a record that someone reported an injury at the scene.
2. Photograph the cars where they stopped. Both plates, both bumpers, the space between the cars, the lane, the signal, the skid marks. Then move to the shoulder.
3. Exchange the information the law requires. Name, address, driver’s license number, vehicle identification number, and proof of insurance, under California Vehicle Code section 16025.
4. Get one witness. A name and a phone number is enough. A neutral witness settles a fault argument faster than any photograph.
5. Say nothing about fault. Not “I’m sorry”, not “I stopped short”, not “I’m fine”. You do not know yet what is wrong with you.
6. Go to an urgent care or an emergency room the same day. Tell the doctor every part of your body that hurts, not only the worst one.

What California requires you to do

Rear-end crashes get treated as minor, so the paperwork gets skipped. Two of these deadlines are legal obligations that run whether or not the crash was your fault. Missing the DMV report can cost you your license under the state’s financial responsibility law, separate from anything that happens with your claim.

The sources, in order: Vehicle Code section 20008 requires a written report within 24 hours when a crash injures or kills anyone. Vehicle Code section 16000 and the DMV’s SR-1 page require the SR-1 within 10 days for any injury, any death, or property damage over $1,000, regardless of who caused it. Government Code section 911.2 gives you six months to present a claim against a public entity. Code of Civil Procedure section 335.1 gives you two years for the injury, and section 338(c) gives you three for the property. If you need the collision report itself, a party of interest can request it with form CHP 190 from the California Highway Patrol, or from the police department that wrote it.

Why the rear driver is usually liable

There is no California statute that says “the rear driver is always liable”. What exists is a duty. Vehicle Code section 21703 says a driver shall not follow another vehicle more closely than is reasonable and prudent. Section 22350, the basic speed law, says no one may drive faster than is reasonable for the traffic and the road. And Civil Code section 1714 makes everyone responsible for harm caused by a want of ordinary care.

Put those together and the driver who hit you has to explain why they could not stop. Most of the time they cannot, which is why liability in these cases is argued less often than people expect. What gets argued is the injury.

When the rear driver is not the only one at fault

California is a comparative fault state. A jury can assign a share of the blame to you and reduce your damages by that share, and under Civil Code section 1431.2, adopted by Proposition 51, each defendant pays only its own percentage of the non-economic damages, meaning pain and suffering. Comparative fault means fault is divided by percentage instead of being all or nothing. The arguments an insurer raises against a stopped driver are narrow and specific:

• Your brake lights or tail lights were not working.
• You cut in front of the other car and then braked, so the safe distance was never there to keep.
• You reversed into them, which turns the collision into a different case entirely.
• You stopped in a live traffic lane after the hazard cleared, or stayed stopped long after there was a reason to.
• There was a third car. A chain reaction moves fault to whoever started it, and the driver directly behind you may be a victim too.

None of those are common, and all of them are easier to defeat with the photographs you took in the first ten minutes than with anything you say six months later. If fault is being disputed in your case, our guide on who is at fault in a rear-end accident walks through how the evidence is weighed.

The injuries that show up days later

In our cases the fight is rarely about who hit whom; it is about whether an impact that left a scuffed bumper could have hurt someone. That argument works on adjusters and it works on juries, and the only answer to it is a medical record that starts the day of the crash.

• Whiplash. The head is thrown forward and snapped back, straining the neck muscles and ligaments. Stiffness, headaches, and reduced range of motion often peak on day two or three.
• Disc injuries. A herniated disc is a spinal disc pushed out of position, pressing on a nerve. It shows up as pain running down an arm or a leg, or numbness in the hand or foot.
• Concussion. You do not have to hit your head. Trouble concentrating, light sensitivity, and sleep changes in the week after a crash belong in front of a doctor.
• Shoulder and knee injuries. From bracing against the wheel and the floorboard, and commonly missed while everyone is looking at the neck.
• Anxiety about driving. Real, treatable, and part of the claim when it is documented by someone qualified to document it.

We cover the full range in our guide to car accident injuries. The rule at this stage is short: report every symptom at the first visit, and do not stop treatment because you are starting to feel better. A three week gap in the records is worth more to the other side than any argument they can make.

Proving a small impact still hurt you

There is a standard argument in every rear-end file: the property damage was minor, so the forces were minor, so the injury is not real. It is made with photographs of a scuffed bumper and it is made in almost every one of these cases.

Four things defeat it, and all four are built in the first month. A medical visit on the day of the crash, listing every symptom rather than the loudest one. A treatment record with no gaps, because three quiet weeks get read as recovery. A treating physician who states in the chart what caused what. And a photograph set that shows more than the dent: the position of the cars, the debris, the seat and headrest, and the interior. What makes the argument worse is the opposite: waiting three weeks, then starting treatment somewhere found through an advertisement.

What to say to the other adjuster

They will call within a few days and they will be pleasant. They are also building a file. You are not required to give the other driver’s insurer a recorded statement, and there is rarely a reason to give one early, when you still do not know your diagnosis.

The first offer usually arrives before your treatment is finished, which is why it is low. It is a negotiating position, not a valuation. Our post on dealing with insurance after an accident goes through the deadlines the law puts on the insurer and what to do when they are missed.

When the other policy is too small

For any California auto policy issued or renewed on or after January 1, 2025, the minimum liability limits are $30,000 for one person’s injuries, $60,000 for everyone hurt in the crash, and $15,000 for property damage, under Vehicle Code section 16056 as amended by Senate Bill 1107. Those are the floor, and plenty of drivers carry exactly the floor. One ambulance ride and one MRI can pass $30,000.

That is what underinsured motorist coverage is for. It sits on your own policy, it is governed by Insurance Code section 11580.2, and it covers the gap between the at-fault driver’s limits and what your injuries are worth. Check your declarations page, the summary page of your policy, for “UM” and “UIM” today, not after the next crash. Those are the uninsured and underinsured motorist lines. If the at-fault driver had no insurance at all, that same coverage is what stands between you and paying for your own treatment.

Treat it as a real crash

Treat it as a real crash from the first minute. Call 911, photograph the cars before they move, exchange what the Vehicle Code requires, and get examined the same day. File the SR-1 inside 10 days, tell your own insurer, and keep the other driver’s adjuster to the date, the place, and nothing else. Then let your treatment finish before anyone puts a number on it.

If you are already past some of that, none of it is lost. Start the medical record today and write down what you remember while it is still close. Our Los Angeles car accident lawyer page explains how a claim is built from here, and there is no fee unless we recover.