The Truth in Lending Act, known as Regulation Z, requires creditors disclose information about their terms and costs to promote the informed use of consumer credit. Section 226.25 requires creditors to retain all evidence of compliance with Regulation Z, excluding the advertising requirements, for 2 years after the date the disclosure is required.
Link to Regulation: https://www.ecfr.gov/cgi-bin/text-idx?SID=2d9f0ddbc90c08024c683e2d3d10abf0&mc=true&node=pt12.3.226&rgn=div5#se12.3.226_125