Do You Qualify for the Lower National Health Insurance Rate? Your First Year Back in Japan

What the ward office actually bills you on

National Health Insurance and long-term care insurance premiums are both set from your previous year's Japan-taxable income, recalculated every fiscal year from April, which is why a returnee's first bill often looks arbitrary rather than wrong.

This article picks up where re-enrolling in health insurance and long-term care insurance leaves off. That piece covers the 14-day registration clock, who enrolls where, and the retroactive-billing trap. This one stays narrowly on the number itself: how the premium is calculated, which reduction band you actually land in, and the filing that decides it. If you have not yet registered your address or opened an insurance card, read that article first.

Every municipality prices National Health Insurance from two parts: an income-based portion, a percentage of your assessed income from the prior tax year, and a per-capita portion, a flat amount charged per enrolled household member. Long-term care insurance for residents aged 65 and over works differently again, sorting each person into one of roughly 15 to 19 income stages, each a multiple of a locally set base amount. Both systems pull the same input: the income figure sitting on your municipal resident-tax record.

The problem for a returnee is that this record is usually empty. If you were living overseas the previous calendar year, no Japanese municipality was tracking your income, so the field the system needs is blank rather than zero. A blank is not automatically treated as zero. Until the ward has something on file, it may not be able to confirm you qualify for any reduction, and a returnee who assumes the low first-year premium happens automatically can end up billed at the full, undiscounted rate instead.

The zero-income trap that costs the reduction

Japan's National Health Insurance reduction bands only apply once every insured household member's income, including "no income," is on record with the municipality.

The Ministry of Health, Labour and Welfare's premium framework builds in a 7-wari, 5-wari, or 2-wari reduction (70%, 50%, or 20% off the per-capita portion) for lower-income households, judged against thresholds tied to total household income and the number of insured members. What trips up returnees is a rule that sits underneath those bands: if any household member who should be enrolled has not filed an income record for the assessment year, even a record that says the income was zero, the reduction is not applied to that household at all.

This is not a special penalty aimed at returnees. It is the same rule that catches a retired long-term resident who simply never filed anything because there was nothing to report. The fix on both sides is identical: file a municipal income declaration (often called a juuminzei shinkoku, separate from a national tax return) stating the income was zero for the relevant year, even though no tax was owed and no return was legally required. Once that declaration is on file, the ward can run the reduction calculation; until then, it generally cannot.

The instructions for this vary by municipality, and some wards prompt new residents to file it as part of the moving-in process while others do not raise it unless asked. The safe move for a returnee with no prior-year Japan income is to ask directly at the tax counter, on the same visit as the National Health Insurance enrollment, whether a zero-income declaration is needed to qualify for the reduction.

So how much does the reduction actually save you?

Kawasaki City's FY2026 (Reiwa 8) rates make the size of the reduction concrete: a single-person household that files correctly can pay roughly three-tenths of what an unfiled household is billed for the same per-capita charge.

Kawasaki assesses National Health Insurance on two components rather than three: an income-based portion and a per-capita portion, with no separate flat per-household charge. For FY2026, the per-capita portion for a resident under 75 comes to ¥43,261 for the medical portion plus ¥15,306 for the late-elderly support portion, a combined ¥58,567 per enrolled person before any reduction and before the separate long-term care portion that applies to those aged 40 to 64. The income-based portion adds a further percentage of assessed income on top (8.26% for medical, 2.89% for support), and for a returnee with no prior-year Japan income, that portion is generally zero.

The reduction bands apply only to the per-capita figure, and the national cabinet order that sets the thresholds was itself revised for FY2026, which is one more reason a figure copied from an older year can be wrong even if the arithmetic is right. A single-insured household whose total assessed income sits at or below ¥430,000 qualifies for the 7-wari reduction and pays 30% of the per-capita charge. The 5-wari line sits at roughly ¥740,000 (the ¥430,000 base plus ¥310,000 per insured household member), and the 2-wari line at roughly ¥1,000,000 (the same base plus ¥570,000 per insured member); both multipliers rose slightly from the prior fiscal year. A single returnee filing a zero-income declaration typically clears the 7-wari threshold outright.

Does turning 65 mean a different, higher bill?

For residents aged 65 and over, Kawasaki's long-term care insurance runs on a 19-stage table built from a single base amount that stays fixed for a three-year period, and a returnee's stage still depends on the same tax record that decides the National Health Insurance reduction.

Kawasaki's base annual amount (kijungaku) covers the three-year period from FY2024 through FY2026 (the ninth kaigo-hoken period) at ¥79,097, worked out to roughly ¥6,591 a month, and the city's own published stage table confirms this base amount carries through FY2026 (Reiwa 8) without a mid-period change. Stage 1, reserved for residents on livelihood protection or receiving the old-age welfare pension in a non-taxed household, pays 0.285 times the base, or about ¥22,540 a year (around ¥1,878 a month). Stage 3, for a non-taxed household with combined pension and other income up to ¥1.2 million, pays 0.382 times the base, about ¥30,210 a year. A household confirmed as fully non-taxed, with modest or no income, generally lands in one of these lower stages rather than at the base rate.

The stage cannot be assigned confidently until the ward confirms the household's non-taxed status from the resident-tax record, the same record that National Health Insurance reads. A returnee who has not filed anything after moving in risks being provisionally treated at a higher stage while the office waits to confirm the household's actual position, then adjusted once the filing lands. Filing promptly, at the same visit as the health insurance paperwork, is the practical way to avoid paying at a higher stage than the household actually qualifies for.

Above these lower stages, Kawasaki's table climbs by income band up to Stage 19, at roughly ¥261,020 a year for households with assessed income of ¥30 million or more. Most returning retirees on a modest pension sit well below that end of the table, but the exact stage still has to be confirmed at the kaigo hoken counter for the household's actual figures; the numbers here are Kawasaki's own published bands, and every other municipality sets its own base amount and stage cutoffs.

Filing the declaration that unlocks it

The declaration that unlocks both the National Health Insurance reduction and the lower long-term care stage is usually a separate form from a national income tax return, and it has to be filed even when no tax is owed.

Most municipalities operate this as a municipal citizen tax (shiminzei) or resident tax (juuminzei) declaration, filed at the tax division of the ward or city office rather than with the national tax agency. It asks each adult household member to state their income for the relevant year, and "zero" is an acceptable, expected answer for a returnee who was not earning in Japan. Filing it does not create a tax bill; it creates the record the insurance divisions need to apply a reduction.

Bring the same basics as the health insurance enrollment: your residence card or passport, proof of your moving-in date, and, if you have it, documentation of when you left and returned to Japan. If your household includes a working spouse or another member with income, that person's income also needs to be on file, since the reduction band is judged on the household's combined position, not on any one person in isolation.

Ask at the counter which fiscal year the declaration should cover. Because the assessment year runs on Japan's April-to-March calendar and looks at the previous calendar year's income, a returnee arriving partway through a year may need to file for a period that only partly overlaps their time in Japan; the ward office confirms the exact year to file for based on your registration date.

What changes in year two, and what does not

The premium recalculates every April on the prior calendar year's Japan resident-tax record, so a first-year figure built on an empty record is not the number you keep once a full year back in Japan is on file.

Your year-one premium is generally low not because of any special returnee discount, but because the record it is built on structurally cannot include anything from before you were a Japan resident for tax purposes. Once your first partial or full calendar year back in Japan closes, that year's actual income, whatever it turns out to be, becomes the basis for the following April's recalculation.

For a retiree whose only income is a foreign-sourced pension, whether that pension counts toward your Japanese resident-tax assessment depends on your tax residency status and can involve a tax treaty, and this is a genuine grey area that varies by individual circumstance rather than a single rule this article can state safely. Confirm your specific position with the municipal tax division or a tax professional rather than assuming either that foreign pension income is invisible to Japan or that it is automatically taxed the same way domestic income would be.

What is predictable is the mechanism, not the outcome: the ward recalculates every April from the prior year's filed record, so a returnee who keeps filing on time, even a zero-income filing, avoids the unconfirmed-income default and gets whichever band or stage the household's actual figures qualify for, year after year.

When to call the ward office instead of guessing

Kawasaki's published rates illustrate how the system works, but every municipality sets its own per-capita amount, its own base amount for long-term care insurance, and its own timing for accepting a zero-income declaration.

If you are settling somewhere other than Kawasaki, treat the figures above as a worked example of the mechanism, not a number to copy. Call the National Health Insurance section of your own ward or city office, ask for the current per-capita rate and reduction thresholds, and ask separately at the long-term care insurance desk for the base amount and stage table if you or a household member is 65 or over.

Two situations are worth a direct call rather than a guess: a household that includes both a non-working returnee and a spouse who is still employed, since the reduction band is judged on the combined figures, and a returnee who arrives mid-fiscal-year, since the filing year and the billing start date can land on different calendars. Neither case breaks the mechanism described here, but both change which line of the table applies.

This article does not cover the separate 14-day enrollment process, who enrolls in what, or the retroactive-billing risk if you delay registering your address; the re-enrolling in health insurance and long-term care insurance article covers that ground. For the pension side of a first-year return, including how overseas years affect your Japanese pension record, see pension when returning to Japan, and for the wider monthly budget a returning retiree should plan around, see cost of living in Japan for retirees. For what National Health Insurance still leaves out of pocket at any income level, what National Health Insurance does not cover is the companion piece. The returning to Japan to retire hub sequences all of these steps in order.