State insurance regulations can differ as do insurance company rating systems. Normally though if an injured party's medical expenses exceed the at-fault party's bodily injury policy limits and you must then use your own underinsured motorist coverage your insurance premiums are not affected.

When you are not at fault in an accident and have to use your own coverages typically your rates are not raised but again since state insurance laws and terms of insurance policies can differ, check with your insurance company to find out for certain if your premiums could be affected if you use your own coverages when you are not at fault in an accident.

A typical rule is that any use of coverage is less than the actual cost savings of not using the coverage. The carrier may take into account all claim activity, but most companies don't raise rates unless there is excessive claims.