Retrospective insurance payments are made if a civil servant leaves their position without receiving pension cover. The public authority must pay compulsory contributions retrospectively for the period in which the civil servant did not have any insurance.
You can ask your employer to make these retrospective insurance payments to the Pension Fund. The contributions are annuitised in the year in which the application for retrospective insurance is made. The retrospectively insured period of work counts as time spent as a participant. This is relevant when calculating your disability pension entitlement.