Year-End US Tax Savings Checklist: 401(k), HSA and What Else Moves the Needle

1. Traditional 401(k)

Pre-tax 401(k) deferrals come out of your paycheck, so the change has to happen through payroll before the year ends. The 2026 limit is $24,500. At $100,000 a single filer who defers the full amount lowers federal income tax by $5,390, because the whole contribution comes off income taxed at 22%.

Check your plan's employer match first: contributing enough to receive it is often the highest-value step. Then compare how much room you have left before the limit, and how much of your remaining pay periods that would take.

2. HSA

If you are covered by a qualifying high-deductible health plan you can contribute up to $4,400 for self-only coverage in 2026 ($8,750 for family coverage). At the 22% federal rate a $4,400 contribution saves $968.

Together, a maxed traditional 401(k) and a full HSA lower the example filer's federal tax from $13,170 to $6,812, a saving of $6,358. State tax can save more, or in a few states less: California and New Jersey, for example, do not give a state break for HSA contributions.

3. Traditional IRA

You can generally fund an IRA for a tax year up to the filing deadline the following spring, so this is a decision you can make after the year ends. Whether the contribution is deductible depends on your income and on whether you are covered by a workplace plan: for a single filer covered at work the deduction phases out between $81,000 and $91,000 of modified adjusted gross income in 2026. At $100,000 that means a workplace-covered single filer would not be able to deduct the contribution.

4. Standard deduction or itemizing?

You take the larger of the standard deduction ($16,100 for a single filer) and your itemized total. If you are close to the line, timing charitable gifts or other deductible expenses into one year can tip the balance. The deduction for state and local taxes is capped at $40,400 for most filers in 2026, so check the current rule rather than assuming an older figure.

5. Check your withholding

Your employer withholds tax based on your W-4. If you have had a major change this year, such as a raise, a second job or a marriage, your withholding may be off. It is easier to adjust now, while there are pay periods left, than to face a bill or a very large refund when you file.

6. Know your state's rules

The tax saving from these steps depends on your state. Most states follow the federal treatment of a 401(k), but Pennsylvania and New Jersey tax 401(k) deferrals, and a state with no income tax gives no state saving at all because there is none to reduce. The state page for your state lists what its estimate includes.

What this checklist does not cover

This is not personal advice. It leaves out investment gains and losses, self-employment income, business deductions, credits and many other things that can change your bill. Use the calculator to see the effect of these deductions at your own income, and speak with a qualified tax professional for anything complex.