Medicare SNF 100-Day Benefit & Coinsurance Calculator

What it is

A deterministic, in-browser tool for senior-care discharge planners, SNF billing, elder-law and senior financial planners. Splits the covered SNF days used in a Medicare Part A benefit period into the three statutory tiers - days 1-20 fully covered ($0/day), days 21-100 at the DATED daily coinsurance, and days beyond 100 not covered (the patient pays the full cost) - and computes the exact coinsurance owed = (covered days in the 21-100 window) x the daily rate. It also does the 60-consecutive-days-out benefit-period RESET calendar math (Social Security Act 1812/1861; 42 CFR 409). No API, no key, no network, no AI - every figure is exact integer-day arithmetic / UTC calendar date math citing its rule. The daily SNF coinsurance is a DATED input you confirm in the CMS notice for the benefit year (a wrong year never silently mis-bills because the rate used is always shown), and the 3-day qualifying inpatient stay is flagged - not assumed. Not legal, tax, financial, benefits, or medical advice.

Honest scope

Authorities cited

• Social Security Act 1812(a)(2) (42 USC 1395d) - Part A coverage of up to 100 days of post-hospital extended care (SNF) services in a benefit period.
• Social Security Act 1861(i) (42 USC 1395x(i)) - "Post-hospital extended care services": requires a prior inpatient hospital stay of at least 3 consecutive days and SNF admission generally within 30 days.
• Social Security Act 1861(a) (42 USC 1395x(a)) - "Benefit period": begins on admission and ends after 60 consecutive days during which the individual is not an inpatient of a hospital or SNF.
• Social Security Act 1813(a)(3) (42 USC 1395e(a)(3)) - The daily SNF coinsurance for days 21-100 equals one-eighth of the inpatient hospital deductible.
• 42 CFR 409.61(a) - Coverage tiers within the benefit period: days 1-20 paid in full; days 21-100 subject to the daily coinsurance; no payment beyond 100 days.
• 42 CFR 409.85 - SNF coinsurance amount for the 21st through 100th day of extended care services in a benefit period.
• 42 CFR 409.60(b)(1) - A benefit period ends after 60 consecutive days out of a hospital and a SNF; a new benefit period may then begin (no limit on the number).
• 42 CFR 409.30(a)-(b) - Qualifying 3-consecutive-day prior inpatient hospital stay and the 30-day SNF admission requirement for post-hospital extended care.
• CMS Medicare Parts A & B Premiums and Deductibles (annual Federal Register notice) - The daily SNF coinsurance amount, set each year: $185.50 (2021), $194.50 (2022), $200.00 (2023), $204.00 (2024), $209.50 (2025). Confirm the notice for your benefit year.