401(k) vs HSA: Which Lowers Your Paycheck Taxes More in 2026?

Answer first: a payroll HSA dollar beats a 401(k) dollar for tax savings. Both escape federal income tax, but only the HSA also escapes the 7.65% FICA hit — because 401(k) deferrals legally remain Social Security and Medicare wages. At a 22% bracket, $1,000 to an HSA saves ~$296.50 in tax; $1,000 to a 401(k) saves ~$220.

2026 limits at a glance

Account	2026 limit	Skips income tax?	Skips FICA?
401(k) elective deferral	$24,500	Yes	No
HSA (single / family)	$4,400 / $8,750	Yes	Yes, via payroll
Traditional IRA	$7,500	Yes (at filing)	No — and never touches your paycheck

Why most calculators get this wrong

Many paycheck tools subtract 401(k) from FICA wages, understating Social Security and Medicare by up to $1,874 a year at the max deferral ($24,500 × 7.65%). Others lump HSA with 401(k) and miss the FICA savings. The error is invisible until you compare against a real pay stub — then nothing reconciles.

The priority order for 2026

401(k) to the full employer match — an instant 50–100% return no tax trick beats.
HSA to the max ($4,400 / $8,750) — triple tax advantage, and FICA-free going in.
Back to the 401(k) up to $24,500 for the income-tax shield.
IRA ($7,500) at filing time if eligible — no paycheck effect, still valuable.

Watch the match trap

Some employers match per paycheck, not per year. Max out a 401(k) by October and November–December paychecks may earn no match. Spread contributions across all pay periods unless your plan has a true-up provision — check the summary plan description.

Conclusion

Same paycheck, different plumbing: route dollars through the HSA first for maximum tax efficiency, the 401(k) for match and capacity. Model both with the paycheck calculator's independent sliders and see each tax line move.

Frequently Asked Questions

Does 401(k) reduce FICA taxes?

No. 401(k) elective deferrals reduce federal (and usually state) income tax but remain Social Security and Medicare wages. Only cafeteria-plan benefits like payroll HSA/FSA contributions escape FICA.

What are the 2026 contribution limits?

401(k): $24,500 employee elective deferral (plus catch-up if 50+). HSA: $4,400 single / $8,750 family coverage. IRA: $7,500 — but IRA contributions do not reduce paycheck withholding since they happen outside payroll.

Is HSA better than 401(k)?

For pure tax efficiency, payroll HSA dollars beat 401(k) dollars: they skip income tax and FICA, grow tax-free, and withdraw tax-free for medical costs. But HSAs require a high-deductible plan and have lower caps; 401(k)s add employer matches. Most people should take the full match first, then fund the HSA.

How much does maxing a 401(k) save on taxes?

At a 22% marginal rate, a $24,500 deferral saves about $5,390 in federal income tax (plus state). It saves $0 in FICA. An HSA dollar at the same bracket saves ~29.65 cents (22% + 7.65% FICA).

Do 401(k) contributions reduce state income tax?

In most states, yes — they start from federal AGI which already excludes deferrals. A few states differ, so check your state page for the exact treatment.

Where can I model both side by side?

The paycheck calculator has separate 401(k) and HSA/FSA sliders with FICA-correct math — move each and watch the federal, FICA, and state lines respond independently.