Form 1099-R reports distributions from retirement accounts — IRAs, 401(k)s, pensions, and annuities. Box 1 shows the gross distribution; Box 2a shows the taxable amount; Box 7 contains a distribution code that tells the IRS the reason for the withdrawal. If code 1 appears and you're under 59½, the 10% early withdrawal penalty likely applies. Rollovers are also reported on 1099-R but may be non-taxable if done correctly. Always review your 1099-R carefully before filing.