Roth conversions before 65 have a hidden second price
Filling a low bracket with a Roth conversion looks free — until you remember marketplace coverage is means-tested. Here's how losing an ACA subsidy can add nine points to your effective marginal rate.
If you retire before 65, health insurance comes from the individual market — and the premium tax credit (PTC) that makes it affordable is means-tested. That turns a Roth conversion into a two-part transaction.
The visible part
A Roth conversion moves money from a traditional IRA or 401(k) into a Roth account. You pay ordinary income tax on the converted amount now, and it grows tax-free afterward. If you're in a low bracket in early retirement, filling that bracket with conversions is one of the most reliable moves in the toolkit.
The hidden part
While you're under 65 and buying marketplace coverage, every dollar of extra income can also reduce your premium tax credit. In the range where the credit phases out, the marginal cost compounds:
- Federal income tax: say 12% or 22%
- Plus lost subsidy: meaningful additional cents per dollar, rising as you approach the cliff
Add them together and a conversion that looks like a 22% decision can behave like a 30%+ decision — which may still be worth it, but only if you can see the full number.
The cliff
The subsidy structure has hard edges, not smooth ramps. Cross the top income band and the credit can fall to zero. A conversion sized without accounting for that can cost far more than the tax bracket suggests.
How to see it
The useful question isn't "what bracket am I in?" It's "what does the next dollar actually cost?" The RetireTaxGuide tax planner stacks federal tax, lost ACA subsidy, IRMAA, and the Social Security tax torpedo into a single marginal-cost view, with the cliffs marked. That lets you size a conversion to stop just short of the expensive line instead of guessing.
Educational only — not tax or financial advice. Subsidy rules have changed repeatedly; verify current law before acting.