Quick answer
Generally, no. You can’t buy a health plan today and date it back to cover care you already got. But the rules allow retroactive coverage in a few specific cases: a new baby or adoption, Medicaid (for up to three months before you apply, shrinking in 2027), COBRA, and Medicare Part A in some situations. Asking an insurer or employer to falsify a coverage date is fraud.
Key takeaways
- Marketplace coverage usually starts on the first of the month after you pick a plan.
- Coverage for a new baby or adopted child can start on the date of birth or adoption.
- Medicaid can cover bills from up to three months before you applied; starting in 2027, that drops to two months for most people and one month for expansion adults.
- COBRA coverage is retroactive to when your job-based plan ended, once you elect it and pay.
- Your coverage doesn’t start until you pay your first premium.
On this page
When retroactive coverage is allowed
| Situation | How far back coverage can go |
|---|---|
| Birth or adoption | To the date of birth, adoption or placement, for marketplace and job-based plans |
| Medicaid | Up to three months before the month you applied, if you were eligible then (two months, or one for expansion adults, starting in 2027) |
| COBRA | To the day your job-based coverage ended, if you sign up within 60 days and pay |
| Medicare Part A | Up to six months before you apply, but not before you turned 65 |
When coverage normally starts
- Open enrollment: On HealthCare.gov, sign up by December 15 for coverage starting January 1. Sign up by January 15 for February 1.
- Special enrollment: Coverage usually starts the first of the month after you pick a plan. If you’re losing coverage and pick a plan before it ends, the new plan can start right after. See qualifying events and how long it takes to get health insurance after applying.
- Job-based plans: Coverage starts when your employer’s plan says, within 90 days after you become eligible.
Coverage doesn’t take effect until you pay your first premium. Pay it by your insurer’s deadline.
What you can’t do
- Buy a plan after an accident or diagnosis and ask for it to start earlier.
- Ask an employer to change the date your coverage ended, or started, on paper.
- Keep an ex-spouse on your plan after a divorce when they’re no longer eligible. The plan may cancel their coverage and ask for claims to be repaid. See can a spouse be dropped from health insurance while still married and covering all family members under the same policy.
Falsifying dates to get claims paid is insurance fraud.
What to do if you had care without coverage
- Check Medicaid. If your income qualifies, Medicaid may pay bills from the months before you applied.
- Elect COBRA if you lost job-based coverage in the past 60 days.
- Ask the hospital about financial assistance. Nonprofit hospitals must have financial assistance policies.
- Negotiate the bill or set up a payment plan.
- Get covered going forward. If you’re in a special enrollment period, pick a plan now. If you’re 65, see health insurance for the elderly.
When you shop, compare plan levels and insurers; see comparing health insurance. If you’re changing plans, see how to switch health insurance companies to avoid a gap.
Don’t wait until you need care: compare plans by ZIP code.
Frequently asked questions
Can I get health insurance that covers a past hospital bill?
Usually not, unless Medicaid’s retroactive coverage applies, or you elect COBRA within your 60-day window.
Does a new baby’s coverage start at birth?
Yes. If you add your baby within the special enrollment window, coverage can start on the date of birth.
What if I miss a premium payment?
Marketplace enrollees with tax credits get a three-month grace period. If you don’t catch up by the end, coverage ends back to the end of the first month.
Sources
This article is general information, not legal or insurance advice. Last reviewed September 2026.