Puerto Rico residents face the same premiums and the same brackets as everyone else on Medicare. There is no separate table and no separate surcharge. Two other things are different, and both catch people out. Income you kept off your federal return under section 933 is added straight back when Social Security works out the income figure behind IRMAA. And Part B does not arrive on its own: you have to ask for it.
IRMAA is a surcharge added to your Medicare Part B and Part D premiums when your income two years earlier was above a threshold. Living in Puerto Rico does not change the thresholds, the standard premium, or the surcharge amounts. It changes two other things.
The income figure behind IRMAA is not something Medicare defines for itself. It is written into the statute. 42 U.S.C. 1395r(i)(4)(A) defines modified adjusted gross income as adjusted gross income “determined without regard to sections 135, 911, 931, and 933 of such Code”, increased by the interest you received or accrued during the year that is exempt from tax.
Section 933 is the Puerto Rico one. For a bona fide resident of Puerto Rico it keeps income from sources within Puerto Rico out of federal gross income, which is why that income never reaches the adjusted gross income line of a federal return. Medicare is told to work the number out as though section 933 were not there.
The practical effect is an order of operations that surprises people. Start with adjusted gross income, Form 1040 line 11. For a bona fide resident whose income is mostly Puerto Rico source, that line can be small, or zero, or there may be no federal return at all. Then add back what section 933 excluded. Then add tax-exempt interest on top. The result is the number Social Security compares against the thresholds.
So a near-empty federal return is not protection from IRMAA. The surcharge can be set from an income figure that appears nowhere on the return you filed. If you are used to treating your federal return as the answer to what your income is for Medicare purposes, this is the case where it is not.
One thing is already in your AGI and is not added back: pay for services performed as an employee of the United States or one of its agencies. Section 933 never excluded that in the first place, so it was on your return all along.
To run the arithmetic on your own figures, use the MAGI calculator. Enter your adjusted gross income, your tax-exempt interest, and the amount you excluded in the field for excluded foreign and U.S. territory income. For everything else that does and does not feed the number, read what counts as MAGI.
All of the above assumes section 933 applied to you, which it does only for a bona fide resident of Puerto Rico. That test is set by the IRS, it is more involved than a page like this could fairly compress, and getting it wrong changes your federal return as well as your Medicare premium. The IRS sets it out in Publication 1321, and a tax preparer who works with Puerto Rico returns is the right person to confirm it.
If the exclusion did not apply to you, nothing was kept off your return, so nothing is added back and your MAGI is worked out exactly as it is for anyone else.
Almost everywhere else, someone already drawing Social Security at 65 is enrolled in Part A and Part B without lifting a finger. Puerto Rico is the exception. Residents get premium-free Part A automatically and have to sign up for Part B themselves.
Missing that window is expensive and it does not wear off. The Part B late enrollment penalty adds 10% to the standard Part B premium for each full 12 months you could have been enrolled and were not, and you keep paying the increase for as long as you have Part B. It is worked out from the standard premium, before any IRMAA, so the two are separate additions. Having one does not excuse the other, and someone in a bracket who also signed up late pays both.
Social Security publishes a booklet for exactly this situation rather than leaving it buried in general guidance. It covers the enrollment windows, the form, and how to sign up: Medicare in Puerto Rico (SSA publication EN-05-10521).
Sources: 42 U.S.C. 1395r(i)(4)(A) for the IRMAA definition of modified adjusted gross income; 42 U.S.C. 1395r(b) with CMS Medicare costs guidance for the Part B late enrollment increase and how long it lasts; 26 U.S.C. 933 for the Puerto Rico exclusion; SSA publication EN-05-10521, Medicare in Puerto Rico, for Part B enrollment; IRS Publication 1321 for bona fide residency. Informational only, not financial, tax, or medical advice. Last verified August 2026.
IRMAA looks back two years, so your 2025 income sets your 2027 premium. See the projected 2027 IRMAA brackets →