Records retention
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
Federations, CCAs and other participants in the CFC shall retain documents pertinent to the campaign for at least three completed campaigns. For example, documentation regarding the 2014 campaign must be retained through the completion of the 2016, 2017 and 2018 campaigns (i.e. until early 2020). Documents requested by OPM must be made available within 10 business days of the request.
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.