Form 8621 · §1291
The Form 8621 §1291 calculation, explained
How the default 'excess distribution' regime works — allocation across the holding period, the top-rate tax, and the interest charge — with a worked example.
By Danilson Ramos · Founder, Atamatax
Updated July 2026
Takes ~2 minutes — then continues into your full free diagnostic.
The §1291 regime applies when you make no election, and it's the punitive one. Here's how the calculation actually works.
Step 1 — identify the 'excess distribution' (or gain)
An excess distribution is broadly the part of the year's distributions above 125% of the average of the prior three years; a gain on disposition of PFIC stock is treated similarly. The current-year portion is taxed normally — the rest is 'thrown back'.
Step 2 — allocate ratably across your holding period
The throwback amount is spread evenly across each day you held the PFIC.
Step 3 — tax the prior-year portions at the highest rate, plus interest
- Amounts allocated to prior years are taxed at the highest ordinary rate in effect for each of those years.
- An interest charge (like an underpayment charge) is added, dated back to those years.
- The current-year portion is taxed as ordinary income this year.
Worked example
Build it on your own numbers: enter the gain or distribution and your holding period, and the calculator produces the allocation, the back-tax, and the interest charge.
Run the §1291 numbers
Build the worksheet on your figures. Atamatax is tax-preparation software, not a CPA firm, and this is not individualised tax advice.
Authorities cited
- IRC §1297 — IRC §1297 — Definition of a passive foreign investment company
- IRS Form 8621 — About Form 8621 — Information Return by a Shareholder of a PFIC or QEF
- IRC §1291 — IRC §1291 — Interest on tax deferral (excess-distribution regime)
Primary sources (Cornell Legal Information Institute for the US Code and CFR; IRS.gov for forms, procedures, and treaty documents). This page is general information, not individualized tax or legal advice.
Atamatax provides tax preparation support and educational resources. This website does not constitute legal or tax advice.