18 April 2028
Last day to make traditional or Roth IRA contributions counted toward tax year 2027. It lands on April 18 rather than April 15 because April 15, 2028 is a Saturday and DC's Emancipation Day is observed the following Monday. A filing extension does NOT extend it. Verified via IRS Publication 590-A guidance and the 2028 filing-deadline shift, 2026-08.
Retirement Contribution Deadlines calendar