How will OPM compute the amount of lost earnings?
Primary source
Verbatim text below is from the Electronic Code of Federal Regulations (eCFR), a public-domain U.S. government work. Always verify the current version with the eCFR before relying on it for any legal matter.
Full Text
(a) Lost earnings will generally be computed in accordance with the Board's lost earnings regulations (5 CFR 1606 of chapter VI). However, the FERCCA states that OPM may compute the lost earnings in an alternative manner if such a computation is not administratively feasible. The alternative manner will yield an amount that is as close as practicable to the amount computed under 5 CFR 1606 of chapter VI.
(b) Your employer is required to submit to OPM all information required to compute the amount of lost earnings.
This is legal information, not legal advice. Laws vary by jurisdiction and change frequently. Always verify current law with official sources and consult a licensed attorney in your jurisdiction for advice on your specific situation.