Two tax dates sneak up on retirees every fall. The first is September 15, when third-quarter estimated tax payments are due. The second is bigger: for most people age 73 and up, December 31 is the required minimum distribution deadline for the year.

Handled early, both are simple. Handled late, both can get expensive — and the fixes get narrower as December approaches. Here is the plain-English version of what each date asks of you, and how the two are connected.

One note before we start: this article is education, not tax advice. A tax professional can apply these rules to your specific return, and we recommend exactly that.

September 15: the mid-year checkup on your tax payments

If you pay quarterly estimated taxes, the third payment of the year comes due September 15. The mistake to avoid is autopilot — copying last quarter's number without asking whether your income actually changed. Retirement account withdrawals count as ordinary taxable income, and a sizable one can raise your tax bill, pull more of your Social Security into taxation, and even nudge up future Medicare premiums through the income-related surcharge. If money moved this year, your September payment should know about it.

A common rhythm we see: a retiree takes a large withdrawal in June for a roof or a family gift, then sends the same estimated payment in September as always. The IRS eventually notices the mismatch. A five-minute check in early September keeps the year's payments matched to the year's income.

December 31: the required minimum distribution deadline

A required minimum distribution, or RMD, is the yearly withdrawal the IRS requires from traditional IRAs and most workplace retirement plans once you reach age 73. The math is simpler than it sounds: last December 31's account balance divided by an IRS life-expectancy factor. Roth IRAs are the happy exception — the original owner never owes lifetime RMDs. The unhappy part is the penalty: miss an RMD and the charge can run up to 25 percent of the amount you failed to withdraw, one of the steepest penalties in the tax code.

Timing matters within the year, too. Waiting until the last week of December leaves no room for a processing hiccup, a form glitch, or a busy custodian's backlog. Taking or scheduling the withdrawal by early fall turns a deadline into a non-event.

Turning 73 this year? One choice, two tax years

Your very first RMD comes with extra flexibility — and a trap. If you turn 73 in 2026, you technically have until April 1, 2027 to take that first withdrawal. But your second RMD is still due December 31, 2027. Wait on the first one and you stack two taxable distributions into a single year, which can lift your bracket, expose more Social Security to tax, and trigger a Medicare surcharge two years down the road. Taking the first RMD during 2026 spreads the income across two returns instead. Neither route is automatically right; the point is to run both sets of numbers while the choice still exists.

The withholding shortcut many retirees prefer

There is a second way to prepay the IRS besides mailing quarterly checks: have your IRA custodian withhold taxes directly from the RMD itself. Withholding carries a quirk worth knowing — the IRS treats it as if it were paid evenly across the whole year, no matter when it actually happens. That is why a year-end withdrawal with healthy withholding can cure an underpayment that quarterly logic would penalize. Many retirees use this to simplify or replace estimated payments entirely. Which approach fits your income mix is a question your tax professional can settle quickly.

Your fall checklist, in one place

What this means for you

Late summer is when these problems are still cheap to fix. Check three things this month: whether your RMD is on the calendar, whether your September payment reflects reality, and whether a charitable distribution or other year-end move could trim the bill. Thirty minutes with your numbers — ideally alongside your tax professional — beats a penalty letter arriving in the spring. If a parent handles their own taxes, this checklist makes a kind mid-September phone call.