HSA Calculator: Growth, Tax Savings & Costs in 2026

How your HSA grows over 10 years

On the defaults — self-only, age 40, $4,400 of your own money, $500 from your employer, $2,000 already in, 7% a year, $1,500 a year of care — the balance grows from $2,000.00 to $55,649.27 in 10 years. Each year $4,900 goes in at the start of the year, the balance grows 7%, then $1,500 comes out for care at year-end. The tax saving is $1,524.60 a year, which is $4,400 × 34.65% (22% federal + 5% state + 7.65% FICA).

Check the identities: total money in = starting balance + years × (own + employer) = $2,000.00 + 10 × $4,900.00 = $51,000.00; medical paid from the HSA = 10 × $1,500.00 = $15,000.00; investment growth = balance − total money in + medical paid = $55,649.27 − $51,000.00 + $15,000.00 = $19,649.27; tax saved = own contribution × (federal + state + FICA) = $4,400.00 × 34.65% = $1,524.60 a year; effective cost of your own $44,000 of contributions after tax savings = $44,000.00 − $15,246.00 = $28,754.00. If you spent $0 on medical care the balance would be $76,373.94 — the $20,724.67 difference is the care you paid for plus the growth that care money never earned.

The worked example, line by line

Setup: self-only, age 40, own $4,400.00/yr, employer $500.00/yr, starting balance $2,000.00, return 7%, 10 years, medical $1,500.00/yr, federal 22%, state 5%, payroll funding.

Line 1 — the tax rate. 22% + 5% + 7.65% FICA = 34.65%.

Line 2 — the tax saved. $4,400.00 × 34.65% = $1,524.60 a year, or $15,246.00 over 10 years.

Line 3 — year 1. ($2,000.00 + $4,400.00 + $500.00) × 1.07 = $7,383.00; minus $1,500.00 of care = $5,883.00.

Line 4 — year 2. ($5,883.00 + $4,400.00 + $500.00) × 1.07 = $11,537.81; minus $1,500.00 = $10,037.81.

Line 5 — year 10. ($48,510.53 + $4,400.00 + $500.00) × 1.07 = $57,149.27; minus $1,500.00 = $55,649.27.

Line 6 — the totals. Total money in $51,000.00; medical paid from the HSA $15,000.00; out of pocket $0.00; investment growth $19,649.27; effective cost of your own $44,000 of contributions $28,754.00.

Reverse: the own contribution for a $100,000 10-year balance is $7,400.00/yr (exact $7,399.9956); the forward at the displayed contribution is $100,000.07 — 7¢ over the $100,000 target, which is rounding. The years to reach $50,000 are 10 years (balance after 9 years $48,510.53; after 10 years $55,649.27). The federal bracket for $2,000/yr tax saved is 32.80% (exact 32.8045%); at the displayed 32.80% the tax saved is $1,999.80 — $0.20 under the $2,000 target, which is rounding. The return for a $75,000 10-year balance is 11.75% (exact 11.7487%); at the displayed 11.75% the balance is $75,005.93 — $5.93 over the target, which is rounding. The medical spending that empties the balance in 10 years is $5,527.76/yr (exact $5,527.7550); at that spending the year-end balances are 1855.24, 1700.35, 1534.61, 1357.27, 1167.52, 964.49, 747.24, 514.79, 266.07, 0.00. The employer contribution for a $60,000 10-year balance is $794.29/yr (exact $794.2945); at the displayed contribution the balance is $59,999.93 — 7¢ under the target, which is rounding.

Every branch, checked

Family coverage ($8,750 own): Balance $119,957.92, tax saved $3,031.88/yr, medical paid from the HSA $15,000.00, out of pocket $0.00. Doubling the contribution more than doubles the balance — the extra $4,350 a year compounds for 10 years.

Age 55, catch-up ($5,400 own): Balance $70,432.87, tax saved $1,871.10/yr, medical paid from the HSA $15,000.00, out of pocket $0.00. The $1,000 catch-up adds $14,783.60 to the balance over 10 years.

Return 5%: Balance $49,104.21, tax saved $1,524.60/yr, medical paid from the HSA $15,000.00, out of pocket $0.00. Two points less return costs $6,545.06 of balance — the tax saving does not change, because it depends on the contribution, not the return.

20 years: Balance $161,185.50, tax saved $1,524.60/yr, medical paid from the HSA $30,000.00, out of pocket $0.00. Tax saved over 20 years is $30,492.00 — the second decade adds far more balance than the first, because compounding has longer to work.

Medical $0/yr: Balance $76,373.94, tax saved $1,524.60/yr, medical paid from the HSA $0.00, out of pocket $0.00. Spending nothing on care leaves $20,724.67 more in the account after 10 years.

Direct deposit (no FICA): Balance $55,649.27, tax saved $1,188.00/yr, medical paid from the HSA $15,000.00, out of pocket $0.00. Payroll funding beats direct deposit by $336.60 a year — the 7.65% FICA saving on a $4,400 contribution.

Federal bracket 12%: Balance $55,649.27, tax saved $1,084.60/yr, medical paid from the HSA $15,000.00, out of pocket $0.00. A lower bracket saves less tax — $440.00 a year less than at 22% — but the balance is unchanged.

What the defaults assume

The model assumes contributions go in at the start of each year, the balance grows at the annual return, then the year’s medical expenses are paid from the HSA at year-end. It assumes the tax saving counts the employee’s OWN contribution only, at federal bracket + state tax + 7.65% FICA for payroll funding, and that wages are under the Social Security wage base. It assumes California and New Jersey do not follow the federal HSA deduction at the state level — use a 0% state rate there. The 2026 limits are $4,400 self-only and $8,750 family, with a $1,000 catch-up at 55+; the HDHP minimum deductible for 2026 is $1,700 self-only and $3,400 family. With your own contribution at $0 and only the employer’s $500 a year, the 10-year balance is $0.00 and the HSA pays only $7,592.71 of the $15,000 of care — the employer seed alone cannot keep up with $1,500 a year of care, and $7,407.29 comes out of pocket. At 0% return the balance is $36,000.00 — $2,000 starting plus 10 × $4,900 in, minus $15,000 of care, with no growth at all. At $8,000 a year of care the balance is $0.00 every year-end; the HSA pays $54,570.00 and $25,430.00 comes out of pocket. Over 1 year the balance is $5,883.00. At age 54 the balance is $55,649.27 and at age 55 it is $70,432.87 — the catch-up adds $14,783.60 over 10 years. Rounding convention: totals are computed from unrounded values, so rounded parts may differ by a cent from their rounded sum; the reverses are nearest-value solutions, and the exact unrounded figures ($7,399.9956, 32.8045%, 11.7487%, $5,527.7550, $794.2945) are stated wherever the rounded figures appear.

Output · formula · meaning

Who uses this

• The worker maxing a self-only HSA at $4,400: they learn the balance reaches $55,649.27 in 10 years — and they check the family branch ($119,957.92) to see what covering a spouse adds.
• The 55-year-old starting the catch-up: they learn the extra $1,000 a year adds $14,783.60 over 10 years — and they check the $5,400 branch ($70,432.87) for the full picture.
• The saver choosing payroll or direct deposit: they learn payroll funding saves $336.60 more a year — and they check the direct branch ($1,188.00) for the gap.
• The saver aiming for a $100,000 balance: they learn it takes $7,400.00 a year of their own money — and they check the 20-year branch ($161,185.50) to see what time alone does.

Accuracy & limitations

The math is first-principles: each year the balance is (balance + own + employer) × (1 + return) minus the year’s medical spending, floored at $0; tax saved is the own contribution × (federal + state + 7.65% FICA for payroll funding). The 2026 limits ($4,400 self-only, $8,750 family, $1,000 catch-up at 55+) are from IRS Rev. Proc. 2025-19. What the model cannot do is predict YOUR return: it assumes a fixed annual return every year, no fees, and the same contribution and the same medical spending every year — real life varies on all four. It does not model the HDHP deductible, the out-of-pocket maximum, or the tax on non-medical withdrawals before 65. For this year’s tax break alone, see the HSA tax savings calculator; for the 2026 limits, see the 2026 HSA contribution limits; for using an HSA as a retirement account, see the guide to using your HSA as a retirement account; and for the step-by-step tax-saving method, see the guide to calculating your HSA tax savings. This is a calculator, not tax advice.