What records should I keep, and for how long, in case of an audit?

Keep enough documentation to substantiate everything on your return, and hold it for the period the IRS can still examine you. The general rule is three years from filing, which matches the standard audit window and the deadline to claim a refund. Extend to six years if you might have underreported income by more than 25%, and keep records indefinitely if you never filed or filed fraudulently. Save W-2s, 1099s, receipts for deductions, charitable acknowledgment letters, mortgage interest statements, and records of estimated payments. For investments and property, keep cost-basis records until years after you sell, since you need them to calculate gains. Home improvement receipts matter for the eventual sale of your house. Digital copies are fine and far easier to manage. A simple labeled folder per tax year — physical or cloud — turns a scary audit notice into a quick, organized response.