The best tax move most people miss isn’t a clever April loophole — it’s the boring, powerful work of lowering your taxable income before the year ends. Every dollar you route through a pre-tax account is a dollar your brackets never touch. Here are the real levers, in the order I’d pull them.
Why lowering AGI is the goal
Your tax is built from your adjusted gross income (AGI) — total income minus certain adjustments. Push your AGI down and you don’t just save your marginal rate on those dollars; you may also unlock other tax breaks that phase out at higher incomes. It’s the highest-leverage number on the return.
The pre-tax accounts that do the heavy lifting
These reduce your taxable income the moment you contribute:
| Account | What it’s for | Tax benefit |
|---|---|---|
| Traditional 401(k) | Retirement | Contributions cut taxable income now |
| Traditional IRA | Retirement | Deductible (income limits apply) |
| HSA | Medical (with an HDHP) | Triple tax-free: in, growth, out |
| FSA | Medical / dependent care | Funded pre-tax; use it or lose it |
A worked example
A single filer earning $70,000 contributes to pre-tax accounts:
| Step | Amount | Taxable income |
|---|---|---|
| Starting income | — | $70,000 |
| 401(k) contribution | −$8,000 | $62,000 |
| HSA contribution | −$3,000 | $59,000 |
| New taxable income | $59,000 |
That $11,000 of contributions drops taxable income by $11,000 — saving roughly $2,400 at a 22% marginal rate, and it’s money going to your own retirement and health, not the IRS. Model the retirement piece in the 401(k) calculator.
Above-the-line vs. itemized
Two kinds of write-off, and the difference matters:
- Above-the-line adjustments (401(k), HSA, traditional IRA, half of self-employment tax) lower your AGI whether or not you itemize — everyone can use them.
- Itemized deductions (charity, mortgage interest, SALT) only help if they beat the standard deduction.
Prioritize the above-the-line levers — they’re available to all and don’t require giving up the standard deduction.
The order to pull the levers
- Capture your full 401(k) match — free money first.
- Max the HSA if you have a qualifying health plan — the most tax-efficient account there is.
- Use an FSA for known medical or dependent-care costs.
- Add a traditional IRA if you’re eligible for the deduction.
- Itemize only if your deductions clear the standard.
Year-end moves worth a calendar reminder
Most of these only count if done in the tax year — and the calendar is unforgiving:
| Move | Deadline |
|---|---|
| Max traditional 401(k) | Dec 31 (via payroll) |
| Fund HSA / IRA | Often up to the filing deadline |
| Charitable gifts (if itemizing) | Dec 31 |
| Harvest investment losses | Dec 31 |
The one people forget is tax-loss harvesting: selling a losing investment locks in a loss that offsets capital gains, plus up to $3,000 of ordinary income a year — quietly trimming your taxable total.
Start before December, not April
The catch with most of these: they’re year-end moves, not filing-season ones. Set the contributions up now. Run your retirement numbers through the 401(k) calculator, see what a credit beats a deduction by, and use the taxes guide to put the whole plan together.
