Insurance companies typically request that a claim be made promptly and within a reasonable amount of time. Some states might have a law or statute that regulates this and thus dictates that the claim must be made within a certain time period, such as a year. You can contact your state's insurance regulator to find out if there is a time limit set for making a claim in your specific state.
Insurance company claims guidelines can differ but in general you do not have to have a police report for an accident in order to file a claim. There are some exceptions though such as if you are placing an Uninsured Motorist claim; your policy may state that a police report is due.
Even if a police report is not required by your insurance company it is helpful to those involved in the accident, as well as the insurance companies, to have a police report taken of the accident. It gives the insurance companies involved with claims resulting from the accident a reference point and the officer's information of what he or she saw at the scene. Insurance providers are aware that police cannot always make it to the scene of an accident and thus then just request the accident participants to exchange information.
If you delay making a report and there is not a police report filed to back up your description of when and where the accident took place than you may need to explain why you delayed reporting the incident to the insurance carrier.
State laws vary also vary on how long one can take to make a claim (or file a lawsuit) once an accident is reported. If there is no statute of limitations that a state mandates then an insurance company has their own internal guidelines that one must follow to place a claim within a prescribed time period. To give you a very generalized time limit for making claims it would normally be required to be done within a year or 2 for physical damages to a vehicle.
There are some states that have specific laws or statutes with regards to filing claims while others may allow your insurance policy and insurers guidelines dictate how long you have to place a claim. This is also true of how long an insurer has to respond to a claim. Some states have specific laws in place while others just say within a reasonable amount of time.
Most all insurance contracts contain provisions stating how long you have to file a claim or suit against the company. This is known as a Contractual statute of limitations. If you do not file a claim or a lawsuit within this time period, you may lose all rights to recover for your claim.
For example, your policy may state that you have one year from the date the claim arose (the date the injury or accident occurred), or from the date the claim was filed, or from the date the claim was denied, to file suit.
It is a good idea to report an accident and file your claim as soon as you can. If you wait to place a claim with your insurance company or a third party claim with another insurer, you may need to explain on why there was the delay. Also the adjuster may want to take a more comprehensive look at your vehicle to make sure no other damage was done after the accident and before the claim was placed.
You should contact your specific insurance carrier's claims department to find out additional details on the time limits there are to report an accident and make a claim.