Comparison · verified July 2026
The Form 8621 Calculator is the deepest tool for one form. It just doesn't prepare the rest of your return.
Expat Tax Tools' Form 8621 Calculator is a professional-grade engine for the single hardest US expat form — §1291 excess-distribution math, QEF and mark-to-market elections, multi-year tracking, and daily foreign-exchange conversion. But it is a calculator, not a tax return: it outputs an IRS-ready Form 8621 PDF that you attach to a return you prepare elsewhere. Pricing is an annual subscription to use the tool plus a per-form charge, which scales down sharply in bulk.
Who the Form 8621 Calculator is for
It is built for tax professionals and confident DIY filers who will assemble the 1040, FBAR, Form 8938 and treaty forms themselves and just want an audit-ready engine for the PFIC piece. If you file many Form 8621s across clients, its per-form pricing scales down further than anything else on the market.
Side-by-side
What you actually get
- Atamatax Winner
- A complete US expat return: 1040 with Forms 2555 / 1116 / 8938, the FBAR, and Form 8621 for each PFIC.
- the Form 8621 Calculator
- Form 8621 only — a calculator that produces the one form, not a return.
Form 8621 depth (§1291 / QEF / MTM)
- Atamatax
- §1291 worksheet with real IRS quarterly interest rates; QEF and mark-to-market elections.
- the Form 8621 Calculator Winner
- Dedicated multi-year PFIC engine, including transitional and expatriation rules — its whole product.
Price for a single PFIC
- Atamatax
- $299 flat — the entire return, Form 8621 included.
- the Form 8621 Calculator
- ≈$59.40/yr to use it + $74.95 per form pay-as-you-go — the 8621 only; you still prepare the return.
Per-form cost at volume (preparers)
- Atamatax
- Flat per-return pricing; not sold per form.
- the Form 8621 Calculator Winner
- Bundles fall to ~$10.95 per form at 500 — the cheapest per-form option anywhere.
FBAR + Form 8938
- Atamatax Winner
- Generated alongside the 1040 package.
- the Form 8621 Calculator
- Out of scope — not produced.
FEIE / FTC / treaty (2555 / 1116 / 8833)
- Atamatax Winner
- Handled as part of the return.
- the Form 8621 Calculator
- Out of scope — Form 8621 only.
Free draft before you pay
- Atamatax Winner
- Full draft is free; you pay only to finalise.
- the Form 8621 Calculator
- Annual subscription required before you can use the calculator.
Filing / e-file
- Atamatax
- PDF package today; e-file Q3 2026 (EFIN pending).
- the Form 8621 Calculator
- IRS-ready PDF to attach to a return; no e-file.
The marked column indicates which product handles the feature more completely as of July 2026. We update this page when their offering changes — tell us if it's out of date.
Bottom line
If Form 8621 is the only thing standing between you and a return you can otherwise handle — and especially if you prepare many of them — the Expat Tax Tools calculator is a precise, professional-grade way to produce exactly that form, and at volume nothing beats its per-form price. If you'd rather not assemble the 1040, FBAR, Form 8938 and treaty forms around it yourself, Atamatax does the same §1291 / QEF / MTM work inside one flat-priced return.
Sources
Try it free
The draft is always free. You only pay when you finalise.
Start the wizard, see your real numbers, and decide from there.