Questions, sources and who PlanMath is for
PlanMath is an educational calculator. It does the math on the numbers you enter from your plans' Summary of Benefits and Coverage. It never tells you what to buy: it shows the math and the trade-off.
Common questions
Is this insurance advice?
No. PlanMath is an educational calculator. It does the math on the numbers you enter from your plans' Summary of Benefits and Coverage. Always check your plan documents and your doctors' networks.
Which year's IRS numbers do you use?
For 2027 plans we use the IRS 2027 HSA limits ($4,500 self-only, $9,000 family) and HDHP thresholds. Until the IRS publishes 2027 tax brackets, we use the official 2026 brackets and update when the new ones come out.
Do you handle family deductibles?
Yes. You choose embedded or aggregate for each plan, and the engine applies each person's costs the way that plan does.
What about California and New Jersey?
Those states tax HSA contributions, so we count only the federal and FICA savings there.
What does the free version do?
Two plans, one scenario, the full-year total in a normal and a worst-case year. Paid ($4 a month, the first 7 days free) adds more plans and scenarios, the best case and break-even, and the all-year deductible tracker.
Is my health data shared?
No. Your plans and claims stay in your account, we never sell them, and you can delete everything in one click.
How is the HSA tax saving worked out?
Your own payroll HSA contribution, capped at the IRS limit minus your employer's money, times your federal marginal rate (from your filing status and household income after the standard deduction), plus 7.65% FICA (1.45% above the Social Security wage base), plus the state rate you enter. States with no wage income tax and California and New Jersey count $0.
Does PlanMath read my plan documents?
You can paste your Summary of Benefits text and AI fills in the plan's fields for you to check. Every field stays yours to confirm or change, and every dollar figure comes from the calculator, never from the AI.
Why rules of thumb fail
"Healthy means HDHP" is a rule about plan types, and your choice is between two specific plans. In PlanMath's sample family on the front page, the HDHP is $1,514 cheaper in the year they expect, and the PPO is $446 cheaper if someone has a bad year and hits the out-of-pocket maximum. Same plans, opposite answers: it depends on the premiums, the employer's HSA money, the copays and the care you expect.
Your year, modelled
Each prescription is named with its tier and monthly cost; each visit type has its own copay; a planned birth or surgery goes in its month. The engine runs every item through each plan in date order: copays before the deductible where the plan says so, the deductible (embedded or aggregate), coinsurance, each person's and the family's out-of-pocket maximum.
All year, after you enroll
Mark the plan you picked and log claims or EOB amounts as they come. PlanMath shows each person's deductible and out-of-pocket progress, what the rest of the year should cost, and whether raising your HSA contribution now pays off. It emails you at half your deductible, when it's met and at the out-of-pocket maximum, and sends a short digest each month. Next October, your comparison starts from this year's real claims.
2027 numbers built in
| IRS figure | 2026 | 2027 |
|---|---|---|
| HSA limit, self-only | $4,400 | $4,500 |
| HSA limit, family | $8,750 | $9,000 |
| Catch-up contribution, 55 and over | $1,000 | $1,000 |
| HDHP minimum deductible, self-only / family | $1,700 / $3,400 | $1,750 / $3,500 |
| HDHP out-of-pocket cap, self-only / family | $8,500 / $17,000 | $8,700 / $17,400 |
Where the numbers come from
- HSA limits and HDHP thresholds: IRS Rev. Proc. 2026-24 (2027) and Rev. Proc. 2025-19 (2026), cross-checked against HSA Orbit.
- Federal tax brackets and standard deductions: IRS Rev. Proc. 2025-32 (2026). Each fall a daily check looks for the IRS release of next year's brackets and switches only when a second public source shows the same figures.
- Your plans and care: what you type in from your own Summary of Benefits and Coverage, your EOBs and your pharmacy.
Who it's for
US employees and families who choose between an HDHP with an HSA and a PPO at work each fall, and self-employed people on HSA-eligible Bronze plans. It's built for the evening you'd otherwise spend on a spreadsheet, and for the year after it.
Free or paid
| Free | $4 a month | |
|---|---|---|
| Plans compared | 2 | As many as you need |
| Scenarios | 1 | As many as you need |
| Expected and worst-case total | Yes | Yes |
| Best case and break-even | — | Yes |
| Claims tracker and emails | — | Yes |