If you're a US person (citizen, green card holder, or US tax resident) who also holds Indian mutual funds, you've very likely triggered a US tax regime most NRIs have never heard of: PFIC — Passive Foreign Investment Company. Indian mutual funds are pooled investment vehicles earning largely passive income (dividends, interest, capital gains), which is exactly the profile PFIC rules were written to capture, regardless of how ordinary or low-risk the fund itself is by Indian standards.
Why the default treatment is punitive
Absent an election, the IRS's default PFIC tax treatment (the 'excess distribution' regime) is designed to be unfavorable — it taxes gains and certain distributions at the highest marginal rate regardless of your actual bracket, applies retroactive interest charges as if the gain had accrued evenly over your entire holding period, and denies the preferential long-term capital gains rate you'd normally get on a held investment. It's a compliance-forcing mechanism as much as a revenue one: the alternative elections (like a Qualified Electing Fund election) require information Indian mutual funds essentially never provide in the format the IRS wants.
The filing trigger most people miss
Separate from the tax treatment itself, PFIC holdings above certain value thresholds require their own annual filing (Form 8621) — one per fund, in many cases — and this reporting obligation exists independently of whether you actually sold anything or owe any additional tax that year. It's easy to build up a portfolio of several Indian mutual funds over the years without realizing each one is a separate PFIC filing obligation once thresholds are crossed.
The PFIC filing-threshold checker on the Investments & Repatriation page estimates whether your PFIC holdings likely cross the Form 8621 filing threshold; it does not calculate the excess-distribution tax itself, which depends on your specific holding history and requires professional preparation.