Published September 28, 2026. All limits and thresholds below are the IRS's official 2026 figures. This is educational information, not tax advice — confirm your situation with a qualified tax professional.
There is a version of year-end tax planning that is about finding clever loopholes. This is not that article.
This is about the far more common situation: a saver who has left money on the table — unused 401(k) room, an unfunded IRA, a missed RMD, losses that went unharvested — simply because nobody put the deadline on a calendar.
Most retirement tax benefits are "use it or lose it" on December 31. You cannot go back and fill last year's 401(k). So here is the checklist, in priority order, with the exact 2026 numbers.
Why the Last Quarter Matters So Much
Two facts make October, November, and December the highest-leverage planning months of the year:
- Most tax benefits expire December 31. 401(k) deferrals, HSA contributions, Roth conversions, and tax-loss harvesting all key off the calendar year. (The IRA is the rare exception — you have until the April filing deadline.)
- You finally know your income. By fall, you can see your actual taxable income for the year. That is what lets you make a precise Roth conversion or bracket-filling decision instead of a guess.
If you do nothing else this year, do the first four moves below. They are the highest-value and the least complicated.
The 2026 Numbers You Need
Here are the official 2026 limits, so you can see exactly how much room you have left.
| Account | 2026 Limit | Catch-Up (50+) | Super Catch-Up (60–63) |
|---|---|---|---|
| 401(k) / 403(b) employee deferral | $24,500 | $8,000 | $11,250 |
| Total 401(k) incl. employer | $72,000 | — | — |
| Traditional / Roth IRA | $7,000 | $1,000 | — |
| HSA — individual | $4,400 | $1,000 | — |
| HSA — family | $8,750 | $1,000 | — |
| SIMPLE IRA deferral | $16,500 | $3,500 | — |
Source: IRS Notice 2025-67 and related 2026 guidance. Full breakdown in our 2026 IRS contribution limits guide.
Move 1: Max Out Your 401(k) — The Single Biggest Lever
The 401(k) employee deferral limit for 2026 is $24,500. If you are 50 or older, add $8,000. If you are 60–63, the SECURE 2.0 super catch-up lets you add $11,250.
The math that matters: if you are behind on contributions for the year, payroll deferrals are the only way to catch up, and they must come from remaining paychecks. Check your year-to-date deferral on your last pay stub, divide the remaining room by the number of paychecks left, and set the percentage now.
Common miss: people who switch jobs mid-year often lose track of how much they have already deferred — and either over-contribute or under-contribute. The $24,500 limit is per person, not per employer.
Move 2: Fund Your IRA (or Backdoor Roth)
The IRA limit for 2026 is $7,000, plus $1,000 catch-up at 50+. Unlike the 401(k), the IRA deadline is the April 2027 filing deadline — but funding it now means the money compounds a full year sooner.
If your income is too high for a deductible traditional IRA or a direct Roth contribution, this is the moment to consider a backdoor Roth: a non-deductible traditional IRA contribution converted to Roth. It is boring, legal, and one of the most reliable tax-free-growth tools available.
The catch: if you hold a pre-tax IRA balance, the pro-rata rule makes the conversion partly taxable. Model it before you do it — see Roth Conversion Strategies.
Move 3: Take Your RMD — The 25% Penalty Is Real
If you turned 73 in 2026 (or earlier), you must take your Required Minimum Distribution from traditional IRAs and most 401(k)s before December 31.
Miss it and the penalty is 25% of the amount you should have withdrawn — reduced to 10% if you correct it within the correction window. That is one of the harshest penalties in the tax code, and it is entirely avoidable.
Two details people get wrong:
- The deadline is December 31, not April. (Only your first RMD can be deferred to April 1 of the following year — and doing so means taking two RMDs in one tax year, which can push you into a higher bracket.)
See how much 401(k) room you have left
Enter your year-to-date deferrals and paychecks remaining — RetirePro shows the exact year-end catch-up and models a Roth conversion.
Calculate My Year-End Moves →- Your custodian can calculate it, but the responsibility is yours. Do not assume it happens automatically.
Use our RMD calculator to see your number.
Move 4: Harvest Tax Losses
Before December 31, review your taxable brokerage account for positions sitting at a loss. Selling them lets you offset capital gains, plus up to $3,000 of ordinary income per year, with losses carrying forward indefinitely.
Two rules to respect:
- The wash-sale rule. If you buy a "substantially identical" security within 30 days before or after the sale, the loss is disallowed. Buy a similar-but-not-identical fund to stay invested.
- Do not let the tax tail wag the investment dog. Harvest losses on positions you were going to sell anyway. Do not dump a good long-term holding just to book a loss.
Move 5: Consider a Roth Conversion (The Bracket-Filling Move)
This is the move that separates a good year-end review from a great one — and it is the one most people skip.
The logic: if 2026 is a low-income year for you — you retired mid-year, you took a sabbatical, you had a business loss, or you simply have unused room in the 12% or 22% bracket — you can convert traditional IRA money to Roth and pay tax at today's rate instead of a potentially higher future rate.
The window is especially valuable for retirees between retirement and age 73, before RMDs and Social Security fully stack up and push you into higher brackets.
How to size it: fill up to the top of your current bracket, not past it. Going $1 into the next bracket means that dollar is taxed at the higher rate — which is fine if you planned for it, bad if you did not.
Run the numbers in the Roth conversion calculator before you pull the trigger.
Move 6: Max the HSA — The Triple-Tax-Advantage Account
The HSA is the only account that is tax-deductible going in, grows tax-free, and comes out tax-free for qualified medical expenses. For 2026: $4,400 individual, $8,750 family, plus $1,000 catch-up at 55+.
If you have an HSA-eligible plan and are not maxing it, this is often the highest-value dollar you can contribute anywhere. And if you can pay medical costs out of pocket now and let the HSA invest, you are effectively building a second Roth. See The HSA Retirement Strategy.
Move 7: Check Your Medicare and IRMAA Exposure
Two Medicare deadlines land in this window:
- Open Enrollment: October 15 – December 7, 2026 for 2027 coverage. Review your drug plan and Advantage plan — formularies and networks change every year. See Medicare Open Enrollment 2027.
- IRMAA is based on your income from two years ago. A large Roth conversion or capital gain in 2026 can raise your 2028 Part B and Part D premiums. This does not mean "never convert" — it means model the surcharge as part of the conversion decision.
Move 8: Coordinate With Your Social Security Decision
If you are claiming Social Security, remember the earnings test: in 2026, if you are below Full Retirement Age, you lose $1 of benefits for every $2 you earn above $24,480. Year-end is when you can see whether a bonus or extra contract work will trigger a clawback.
And if you have not claimed yet, the 2027 COLA is estimated at 3.6%, with the official number due October 14, 2026. A higher benefit base makes delaying more valuable. Compare ages in the Social Security calculator.
Move 9: Rebalance and Re-Run the Plan
Finally, use the fresh year-end numbers to do two things:
- Rebalance back to your target allocation. A strong year in stocks can quietly push you into more risk than you intended.
- Re-run your retirement plan with actual balances, actual spending, and a slightly higher inflation assumption. A plan built in January is a plan built on stale assumptions by December.
The Checklist, Condensed
| # | Move | Deadline | 2026 number |
|---|---|---|---|
| 1 | Max 401(k) deferrals | Dec 31 | $24,500 (+$8,000 / +$11,250) |
| 2 | Fund IRA | Apr 2027 filing | $7,000 (+$1,000) |
| 3 | Take RMD (age 73+) | Dec 31 | Per IRS tables |
| 4 | Harvest tax losses | Dec 31 | Up to $3,000 vs. ordinary income |
| 5 | Roth conversion | Dec 31 | Fill your bracket |
| 6 | Max HSA | Dec 31 | $4,400 / $8,750 (+$1,000) |
| 7 | Review Medicare | Dec 7 | See plan ANOC |
| 8 | Check SS earnings test | Dec 31 | $24,480 threshold |
| 9 | Rebalance + re-run plan | Dec 31 | — |
The Bottom Line
Capturing your full IRS benefits is not about being clever. It is about being on time.
The saver who maxes the 401(k), funds the IRA, takes the RMD, harvests losses, and fills a low bracket with a Roth conversion will end up with meaningfully more — not because of a loophole, but because they used the room the law already gave them.
Three months is enough time to do every move on this list. Start with the first four, then work down.
Run your numbers first, then act. Open the RetirePro retirement calculator to see your year-end picture, and use the Roth conversion calculator to size the bracket-filling move.
⚠️ Educational information only. This article is not tax, legal, or financial advice. Contribution limits, thresholds, and deadlines are set by the IRS and Congress and can change; verify against IRS.gov before acting. Consult a qualified tax professional about your specific situation.