Amended return (Form 1040-X) — claiming a credit you missed in an earlier year

What this actually is

If you were eligible for EITC, the Child Tax Credit or another refundable credit in a past year and did not claim it, the money is usually still claimable. You file Form 1040-X for that year. The deadline is the LATER of three years after you filed the original return or two years after you paid the tax. That means roughly three filing seasons of back credits are typically still open at any time. This is the single most overlooked money in this whole list, and it is free to claim — VITA volunteers (below) prepare prior-year returns at no charge. Expect 8 to 12 weeks, sometimes 16, for processing; this is slow money, not today money.

Who qualifies, and what trips people up

You must have been eligible in the year you are amending — amending does not create eligibility. Returns filed before the due date count as filed on the due date for the three-year clock. If you never filed at all for that year, you file an original late return rather than a 1040-X. Check status with "Where’s My Amended Return?" or 866-464-2050 after three weeks.