If you had an accident with no other cars involved and filed a claim to insurance with no police report do you have to report this accident to the new company if you get different insurance?

If you don't the new insurance company can cancel your coverage and possibly not cover any of YOUR losses. They might also consider it to be fraud. Any accident less than $750 isn't chargeable, but if you filled a claim with another insurance company your new company would found out even if you don't tell them, when they run your MVR which shows your tickets and previous insurance companies and claim paid.