Yes, FERCCA changes the rules on make-up contributions to the TSP for some individuals.
Before FERCCA, you did not receive lost earnings on any make-up contributions you had withheld from your pay because of a retirement coverage error. You did receive lost earnings on agency contributions made to your TSP account.
Under FERCCA, you can receive lost earnings on your make-up contributions if you choose to stay in FERS. You also continue to receive lost earnings on any contributions your agency makes to your TSP account.
Before you're asked to choose retirement plans, OPM will give you information about your TSP benefits under both CSRS Offset and FERS.
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