A $5,000 penalty for forgetting to take money out of your own retirement account. That’s not a hypothetical — it’s what happens when you miss a required minimum distribution. And it’s just one of the quiet tax traps waiting for retirees who assume the IRS plays by the same rules it did when they were collecting a paycheck.

Here’s what nobody at the IRS is going to call and warn you about: retirement income gets taxed differently than a salary. Your money now comes from Social Security, pensions, IRAs, and investments — each with its own set of rules. Get one wrong, and your tax bill jumps in ways you never saw coming.

The Big Withdrawal Trap

Pull too much from a traditional IRA or 401(k) in a single year, and you don’t just pay tax on that withdrawal. You can trigger a chain reaction. That extra income can push up to 85% of your Social Security benefits into taxable territory. It can also hit you with Medicare surcharges called IRMAA — higher premiums for Part B and Part D that kick in once your income crosses certain thresholds.

The same thing happens with large Roth conversions. Yes, converting to a Roth can be smart long-term. But dumping a big chunk into a single tax year is like volunteering for a higher bracket. Spread it out. Your future self will thank you.

The RMD Penalty Nobody Warned You About

Once you hit 73, the IRS requires you to start pulling money from most tax-deferred accounts every year. These required minimum distributions aren’t optional — miss one, and the IRS slaps you with a 25% excise tax on the amount you should have taken. Correct it fast, and you might get that knocked down to 10%. On a $20,000 distribution, that’s still $2,000 to $5,000 gone for no reason other than a missed deadline.

People miss these because they forget the rule kicks in at 73, or because they’ve got accounts scattered across multiple institutions and lose track. Your brokerage might send a reminder. The IRS won’t.

Selling Investments Without Doing the Math

Sell a stock you’ve held for less than a year, and the profit gets taxed as ordinary income — same rate as your paycheck used to be. Hold it longer than a year, and you get the lower long-term capital gains rate. That distinction alone can mean hundreds or thousands of dollars.

Dump multiple investments in the same year without planning, and you can push yourself into a higher bracket entirely. Before you sell anything, check your cost basis and how long you’ve held it. A little math before the trade beats a big surprise in April.

The Withholding Gap

When you were working, your employer handled tax withholding. In retirement, that safety net mostly disappears. IRA and pension withdrawals don’t always withhold enough — or anything at all — unless you specifically set it up. Show up at tax time owing thousands, and the IRS may tack on an underpayment penalty just to twist the knife.

Fix this now. Either set up withholding on your retirement withdrawals or make quarterly estimated payments. Either way, you stay ahead of the bill instead of behind it.

Medical Deductions You’re Probably Ignoring

If your medical expenses top 7.5% of your adjusted gross income and you itemize, you can deduct the excess. That includes premiums, prescriptions, dental, vision, even certain home modifications. Most retirees take the standard deduction and stop tracking these costs altogether — which means in a year with a surgery or a dental implant, they leave real money on the table.

A New Wrinkle for 2026

The One Big Beautiful Bill Act created new federal deductions, including a senior bonus deduction. But not every state is following along. Some states aren’t adopting the federal changes, which means your federal return and your state return could calculate taxable income differently. One more thing to double-check before you file.

None of these mistakes require bad luck. They just require not knowing the rules — rules the IRS isn’t in any hurry to explain. A couple hours with a tax professional or a good retirement tax checklist can save you more than most people realize. The system doesn’t reward ignorance, but it sure does profit from it.