As in any civil proceeding, workers' compensation claims are subject to a specific statute of limitations, which is set forth by the state.
A statute of limitations is a time frame in which claims must be filed in order to be valid. The idea is courts want to limit the possibility of becoming backlogged with years-old cases for which evidence may have eroded or be non-existent. So for example in Georgia, the general rule is claims for workers' compensation benefits have to be filed within one year of the accident date, or else the right to compensation is barred. This is different from the time limit for other types of personal injury claims, which is two years. That's why injured workers must act quickly to secure benefits.
However, the statute of limitations can be "tolled" or postponed in certain cases. Those include situations in which income or medical benefits have been paid voluntarily by an employer to or on behalf of the injured worker. Claims involving a death have to be filed within one year of the date of death. There are also exceptions made when workers were not aware injuries were work-related.