Doing business with your own insurance company after a car crash can be time-consuming and a hassle. Just imagine what it's like to deal with the insurance company of someone else who crashed into your car. Here are some tips to ensure you maintain your cool — and your sanity — when making a claim with the at-fault person's insurer.

The driver who crashes into your car is responsible for informing his or her insurance company about the incident. However, it's a good idea for you to call his or her insurer because motorists who cause accidents often may be reluctant reporters. So, it is important that you obtain the most complete insurance information from the at-fault person at the scene of the accident: insurance company name, claims phone number, address, and even the insurance agent's name.

You then inform the other person's insurer that you have been involved in a crash with one of its policyholders and tell it about any property damages or injuries. Also, relate only the facts of the accident to the insurer, even if you believe the other driver to be at fault. The police will determine who is at fault and the insurer will make its determination of fault based on the police recommendation, your commentary notwithstanding. (Click to What to do after an auto accident for more on that.)

Although you may feel you are not at fault in the accident, you should contact your own insurance company. This is crucial because it establishes your good-faith accident-reporting effort and, more importantly, can aid you if the other party and/or his or her insurer deny responsibility for the accident. (More on that later.)

Theory vs. reality

Auto insurance, in the simplest terms, is a contract between a motorist and an insurance company in which the company agrees to pay for damages or losses its insured motorist causes. If a motorist damages your car and injures you, his or her auto insurer is responsible for paying you for your damages and injuries. Theoretically, all you should have to do is notify the other party's insurer of your damages and injuries, take the car to a body shop, go to the doctor, and expect the insurer to pay your bills.

Theories are not always put into practice, however. Insurance companies often say you must obtain their authorization to go ahead with vehicle repairs and injury treatments. Taking matters into your own hands can create a payment problem down the road if the insurance company claims adjuster says, "I didn't authorize that." So at least get the insurance company to accept liability before going ahead with repairs. You'll want to get the authorization in writing, so ask the insurer to fax it to you in order to expedite the repairs.

A good strategy to use if the insurer's claims adjuster resists paying for certain car repairs or treatments for injuries because they were not authorized is to remind the insurer that seeking its approval on every repair technique and treatment can cause unnecessary delays, which increase the cost of your claim in the form of vehicle-storage charges and more legwork for the adjuster.

In addition, the at-fault driver's insurance company can't force you to take your vehicle to a specific repair facility. Most states allow auto insurers to recommend auto body shops, but insurers aren't allowed to demand you employ a certain repair facility. The choice is yours.

Pick your battles

Another person's insurer also might say you need to seek payment from your own insurer because it has no evidence of its policyholder's fault. This is why it's a good idea to notify your insurer immediately after the crash. Although most states have made it illegal for an insurer to deny claims without reasonably investigating the facts, or to deny claims when its liability is reasonably clear, you might not be interested in fighting the other person's insurance company.

Hiring a lawyer if you decide to take on the at-fault driver's insurer may be a good idea, especially if you've been seriously injured. (Read When to hire a personal injury lawyer for more on that.) An attorney can help you navigate the sometimes-murky laws that govern insurance. But keep in mind that if you hire an attorney, he or she will take a cut of the settlement he or she helps secure.

When the other driver lies

You might have evidence of the other driver's fault — they may even have admitted it at the scene — yet find your claim denied by his insurance company. Why? Because he's told a version of how the accident happened that doesn't square with yours, and his insurer is standing behind that story all the way in order to avoid paying your claim.

"It happens all the time," says Texas attorney James Holmes. "Remember, the company's first impulse is to say 'no'. The insurance company will wholeheartedly adopt its policyholder's position."

This is especially common in cases where no police accident report was made, showing the importance of calling the police to the scene of any accident. In many states, if an officer at an accident scene determines the damage is minimal (usually less than $500), he will not make an accident report. Body shop estimates for that same accident, however, might run into the thousands of dollars. What now?

"You can't make the police officer write a report," says Holmes. "The best advice in that scenario is to do the officer's job by getting witnesses and all the information from the other driver. Then, get that car to a repair shop immediately, so you can minimize any questions about what caused the damage."

Write down the other driver's address and policy information, together with statements and contact information from any witnesses at the scene. That way, if questions arise later, you'll have a body of evidence gathered at the scene to bolster your stance on how the accident occurred.

Say you took the policeman's word that your damages were minimal and drove off from the scene feeling relieved that nothing worse happened — and only later discover that it will take $2,000 to fix that supposedly minor dent. You didn't think to get witnesses, and you're positive the other driver ran a red light (or a stop sign, or disobeyed some other traffic rule). Now it's your word against his, and not only will his insurance company side against you, but you'll have a hard time changing the insurer's mind without evidence to support your story.

You can ask the insurer to demonstrate how the accident could have happened as the other driver said. Or, if it's a small enough claim and you have extra time, you can drag the other driver to small claims court. "Outside of that, the best hope you've got is to get a lawyer," says Holmes. "Insurance companies know that unless you've gotten serious and hired an attorney, they can tell you 'no', or they can say they'll get back to you. And the longer it drags on, the longer the insurer holds onto its money and the more likely you are to take a compromise."

Another option

If you are involved in an auto accident with another vehicle, and they are the "at-fault" party, making a claim on your insurance policy for payment of damages and injuries likely will require you to pay your collision coverage deductible (assuming you have collision coverage). But if the other person truly is at fault, your insurer likely will subrogate — meaning seek payment from — the other person's insurer to recoup your deductible as well as their payment to you. An insurer also might allow you to make your claim under your uninsured motorist coverage, although in most states that coverage will pay only for injuries. (Click to How to buy uninsured motorist property-damage coverage for more information.)

Your insurance premiums aren't necessarily going to increase at renewal time if you make a claim under your own insurance policy for an accident that wasn't your fault. Most state laws prohibit insurers from surcharging policyholders or raising their premium rates for accidents in which they weren't at fault. However, those laws do not preclude your insurer from dumping your policy at renewal time if you've made a couple of recent claims. If you drive in a high-risk area and are subject to being hit, even if you are not at fault, your insurer might find you too high a risk to insure.

Massachusetts and Michigan differ

So-called "no-fault" states and others that require you to purchase personal injury protection (PIP) have slightly different rules for collecting for your damages and injuries after an accident. For example, your PIP coverage pays for your medical expenses and lost wages, even if you are not to blame for the crash. Receiving your PIP benefits requires you to contact your own insurance company about the accident and to make a claim under your own insurance policy. You'll have to pay a deductible if you make a claim under your PIP coverage.

Massachusetts and Michigan laws take the at-fault party's insurance company completely out of the picture at first. In Massachusetts, crash victims are required to submit a claim for property damages and injuries under their own car insurance policy no matter what. If you are not to blame, your insurer will subrogate the at-fault driver's insurer. Michigan laws go a step further. Besides the requirement to make claims for medical expenses under your own PIP coverage, you have to seek vehicle-damage payments from your insurance company. The only exception is when another driver hits your vehicle while it is properly parked.

Other no-fault states give you the option of contacting the at-fault driver's insurer to recover property-damage payments and medical expenses not paid by your PIP. Check with your insurance agent, or your state insurance department, for the best way to handle any situation.

Can't work? Totaled car? Get paid

If you miss work because of an injury you sustained in a car crash that was someone else's fault, you can expect that person's insurance company to pay for your lost wages. The only limit on the amount of reasonable lost-wages payments you can collect is the at-fault driver's bodily injury liability insurance limit.

If you're hit by a driver whose liability limits are not high enough to cover all of your medical expenses and lost wages, you can make a claim under your own uninsured motorist coverage for the remainder. If you live in a no-fault state, your PIP coverage will pay for your lost wages up to the limits of your coverage.

When another driver wrecks your car beyond repair, you can expect his or her insurance company to pay you the actual cash value of your car before it was totaled. The industry standard definition of actual cash value is "replacement cost" minus "depreciation." Replacement cost is the amount of money it would take to replace your vehicle with a similar one. Depreciation is the amount of money your car has devalued over time.

State laws generally allow insurers to base the actual cash value of your totaled car on the prices of similar vehicles in your area. Insurers often hire outside sources such as ADP Claims Solutions Group, CCC Information Services, or Mitchell International to find out the cost of similar vehicles. The insurer also should pay for the sales tax on the new vehicle that you purchase with the insurance money. (Click to What to do when your auto insurer totals your car for more information.)

Reasonable rental cars

Insurance companies are always looking for ways to shave a few dollars from the cost of a claim, and reimbursements for rental-car costs often are the first to meet the blade. Insurance companies often tell accident victims that they pay only a certain amount per day for rental cars. As a victim of another person's negligence, you have the right to recoup the costs associated with fixing the life disruption you experience, including all of the costs of renting a vehicle while your own vehicle is unusable.

To avoid upsetting your insurance company and subjecting yourself to paying for part of a rental, rent reasonably. Obtain a rental vehicle that is similar to your own and return it promptly when your own vehicle has been fully repaired. Rent a vehicle only if your own is not safe to drive or requires extensive time in the shop. And don't purchase a collision damage waiver from the rental company if your own insurance policy covers damages to rental cars.

If you rent reasonably and the insurer insists on cutting the amount of its reimbursement, ask the insurer to put its reason in writing. Insurers must inform you in writing of their decisions to deny or reduce payments.

Know what you deserve

Knowing your state's prompt-payment law is beneficial. A part of every state's "unfair claims settlement practices act" outlines the time frame in which an insurer must issue you a check for your damages.

Laws vary widely from state to state with many simply mandating a "prompt" payment of claims, while others specify a number of days and the interest owed to you if the insurer fails to pay within the specified period. One last factor to keep in mind: Unfair claims settlement practices acts often do not extend the same rights to you if you're making a claim against another driver's insurance as opposed to making a claim under your own insurance policy.

Writing a matter-of-fact letter to the at-fault person's insurer is a good way to inform it of your expectations and rights. Telling the insurer that you expect it to pay all reasonable costs you incur as a result of the accident, including payment for repairs to or the total-loss value of your vehicle, diminished value of your car, medical expenses, lost wages, and rental-car costs will help smooth the claims process by highlighting the insurer's responsibilities under public policy.