Mio doesn't guess — she does the arithmetic. Enter your annual gross salary and a simple family situation, and Mio estimates your furusato nozei full-deduction limit: the ceiling under which your donations cost you a net ¥2,000 and everything above ¥2,000 comes back as reduced income tax and resident tax. This is a rough estimate for a single-earner employee, not your exact figure — your real limit depends on all your deductions and other income — but it gets you in the right neighbourhood so you don't over-donate.
Assumes a company employee on Shakai Hoken (社会保険) with only salary income, using social insurance ≈ 15% of gross and illustrative deduction amounts. If you have other income, run the numbers again with an official simulator.
| Rough breakdown (estimate) | Amount / year |
|---|
The gift value shown assumes the legal maximum of ~30% of your donation. Actual gifts vary. This is illustrative, not a promise.
Once you know your rough limit, you'd choose a furusato site to browse gifts and donate — compare their simulators and point-back before you pick one. First, read Mio's plain-English explainers below so you don't over-donate.
Mio uses the standard Japanese "full-deduction limit" logic, working backwards from your resident tax:
| Step | What it does (illustrative) |
|---|---|
| 1. Rough taxable income | Gross − employment-income deduction − social insurance (~15%) − basic deduction (~¥480k) − spouse / dependent deductions (¥380k each) − your "other deductions". |
| 2. Marginal income-tax rate | Reads which national bracket that taxable income falls in: 5 / 10 / 20 / 23 / 33 / 40 / 45%. |
| 3. Resident-tax income levy (所得割) | ≈ 10% of a similar taxable base — this is the pool the ~20% cap is measured against. |
| 4. The limit formula | Limit ≈ (resident-tax income levy × 20%) ÷ (100% − 10% − income-tax rate × 1.021) + ¥2,000 |
The 1.021 factor is the reconstruction surtax on income tax. Mio uses illustrative deduction amounts and a ~15% social-insurance estimate, and treats the resident-tax base as roughly equal to the income-tax base. Real resident-tax deductions differ slightly from national ones, so treat the output as a ballpark, not to-the-yen.
Two things trip people up. First, the limit is a ceiling, not a target — if you're not sure, donate a bit under it. Going over doesn't get "clawed back" from your bank, but the amount above your limit simply isn't deducted, so you paid full price for that part. Second, furusato nozei only helps if you actually pay resident tax in Japan — if your income (or taxable income after deductions) is very low, your limit shrinks toward zero and the ¥2,000 may not be worth it.
Mio