Fixing a Year-End Adjustment Mistake in Japan

Last updated: 16 October 2026 · the National Tax Agency’s 2026 year-end adjustment guide · figures for the 2026 tax year

The year-end adjustment (年末調整, nenmatsu chōsei) is your employer working out the year’s income tax in December and settling the difference with what was withheld. When it leaves something out — a form you never handed in, a dependent who changed, a life insurance certificate that arrived late — there are two ways to put it right. Until 31 January of the next year your employer can redo it (年末調整のやり直し), because that is when it has to give you the withholding tax statement (源泉徴収票). After that you file a tax return yourself, and a return that only gets tax back can be filed for 5 years. The one exception runs the other way: if the mistake means too little tax was taken, your employer still has to redo it, even after January. The forms themselves, in English, are in the year-end adjustment guide; to see what the year comes to on your salary, use the take-home calculator.

This is a general explanation for somebody paid a salary by one employer in Japan. Your employer’s payroll and the tax office are the authority on your own year.

First: was there a year-end adjustment at all?

Your employer only does it for an employee who has handed in the dependents declaration (給与所得者の扶養控除等（異動）申告書) by the time it runs, and who is still employed there at the end of the year. Three common cases fall outside it:

• You never handed in the dependents declaration, or you gave it to another employer. Your pay was withheld on the higher column (乙欄) all year, and nothing was settled in December.
• You left your job during the year and had no employer at the end of it. Your last employer gives you a withholding tax statement, and the year is settled only if you file.
• Your salary for the year was over ¥20,000,000. The law takes these out of the year-end adjustment, and you file a return instead.

In all three, the fix is the tax return below, not a redo.

Until 31 January: ask your employer to redo it

The National Tax Agency’s guide for employers lists the cases where a year-end adjustment that has already been done can be done again, and gives the same deadline for each: the end of January of the next year, when the withholding tax statement is due. Those that matter most to employees:

• Your dependents changed after the adjustment and before the end of the year: a child married, or you or a relative came to count as a person with a disability. You hand in the changed form, and the count is redone.
• Your spouse’s income, or your own, turned out different from the estimate the exemption for spouse (配偶者控除・配偶者特別控除) was based on. The same goes for a relative aged 19 to 22 whose special deduction (特定親族特別控除) rested on an estimate of their income.
• A premium or a certificate came late: you paid a life or earthquake insurance premium after the adjustment, or a certificate arrived in January. You hand in the insurance form (保険料控除申告書) with it.
• The home-loan form came late: the form for the home-loan credit (住宅借入金等特別控除申告書) was handed in after the adjustment.

The guide says the employer can redo it in these cases, so ask as soon as you notice; payroll departments are busiest in January. It works the other way too: if your employer adjusted on the strength of certificates you promised by the end of January and they never arrived, it has to redo the adjustment without them and take back the difference.

The end of January limits only a redo that would give tax back. When a redo would collect tax that was too little — a dependent you claimed left your household or turned out to earn too much — the National Tax Agency says the employer has to do it even after the end of January. So in that case tell payroll first, whenever you notice.

A redo usually shows on your January or February payslip, as more tax back or as tax taken. Either way the withholding tax statement you get afterwards shows the corrected year.

After that: a tax return of your own

Once the withholding tax statement has been issued, a correction that gets tax back goes through the tax office, not the employer.

• If you are owed tax — a deduction was left out, you left your job mid-year, the dependents declaration was never handed in — you file a refund return (還付申告). It does not have to wait for the February to March filing season: the National Tax Agency says it can be filed for 5 years, counted from 1 January of the year after the one it is for.
• If you already filed and left something out that would give tax back, the route is a request for correction (更正の請求). After an ordinary return it is generally within 5 years of the filing deadline; after a refund return, generally within 5 years of the day you filed that return.
• If you owe tax — for example, a dependent you claimed turned out not to qualify — start with payroll: the employer redoes the adjustment, takes the shortfall from your pay and gives you a corrected withholding tax statement. If you had already filed a return for the year, check it against the corrected statement. Before the filing deadline you can simply file a corrected return. After it, an amended return (修正申告) is for when you owe more or were refunded too much, and the National Tax Agency asks for it as soon as you know; if the return now shows you paid too much, the route is a request for correction (更正の請求) instead. The tax office can tell you which applies.

For the return you need the withholding tax statement from every employer you had in the year, and the certificate for each deduction you are adding. You can file with e-Tax on the National Tax Agency’s site or on paper at the tax office for your address.

What usually goes wrong for people from abroad

• Relatives living abroad. A dependent outside Japan needs documents proving the relationship and the money you sent, in Japanese or with a translation. When they are missing, the employer leaves that dependent out, and the guide to overseas dependents explains what counts.
• An insurance policy from home. A policy taken out abroad with a foreign insurer does not qualify for the life insurance deduction, so leaving it out was right. The life insurance deduction guide covers which policies do.
• Starting mid-year. If you had another employer in Japan earlier in the year, the new one needs that employer’s withholding tax statement to include the pay; without it, it cannot adjust, and you file.
• Leaving Japan. Leaving changes who settles the year; the guide to the final return and a tax agent covers it.

Questions people ask

My company’s deadline for the forms has passed. Is it too late?

Not for the tax. Ask payroll whether they can still include it: they can redo the year-end adjustment until 31 January of the next year. If they cannot, file a return yourself and claim it there.

Can I still get back tax from an earlier year?

Yes, if the year was overpaid. A refund return can be filed for 5 years, counted from 1 January of the year after the one it is for, so tax for 2026 can be claimed into 2031.

Do I have to file if the correction only gives me money back?

No. A refund return is optional: if you do not file it, the tax office keeps the overpayment and nothing else happens. If the correction means you owe tax, you should file.

Sources

• National Tax Agency — 令和8年分 年末調整のしかた, page 43 (年末調整後に給与の追加払や扶養親族等の異動があった場合の再調整: the cases, and the end of January as the deadline for each). Japanese, opened 16 October 2026.
• National Tax Agency — No.2671 年末調整の後に扶養親族等の人数が異動したとき (when tax was under-withheld, the employer has to redo the adjustment even after the end of January). Japanese, opened 17 October 2026.
• National Tax Agency — No.2665 年末調整の対象となる人 (only employees who have handed in the dependents declaration; who is left out). Japanese.
• National Tax Agency — No.2030 還付申告 (a refund return can be filed for 5 years from 1 January of the next year; after a refund return, a correction request generally within 5 years of filing it). Japanese.
• National Tax Agency — No.2026 確定申告を間違えたとき (更正の請求 generally within 5 years of the filing deadline; 修正申告 when too little was paid). Japanese.
• National Tax Agency — No.7411 「給与所得の源泉徴収票」の提出範囲と提出枚数等 (the statement is due by 31 January). Japanese.