Income tax in Japan: year-end adjustments and what SSW workers need to know

Japan operates a withholding tax system (源泉徴収制度, gensen chōshū seido). Every month, your employer deducts a provisional income tax amount from your gross salary based on an official tax table. This estimated deduction appears on your payslip as 所得税 (shotoku-zei).

Japan has two employment-related taxes that are easy to confuse. Income tax (所得税) is a national tax collected by the Japanese government, calculated on your annual income and withheld monthly. Residence tax (住民税, jūmin-zei) is a local tax collected by your city or ward, calculated based on your previous year's income — it does not appear on your payslip in your first year in Japan, but it will arrive in your second year. Both are handled differently and on different schedules.

Income tax is progressive: the rate increases as your income rises. For the annual income levels typical of SSW workers (roughly ¥2.5–3.8 million per year depending on sector and overtime), you are in the 5% or 10% bracket after standard deductions. Your monthly withholding will approximate this rate but may be slightly over or under depending on the tax table your employer uses.

In December each year, your employer performs a 年末調整 (nenmatsu chōsei, year-end adjustment). This is a reconciliation: your employer calculates your actual tax liability for the full calendar year — accounting for allowable deductions — and compares it against the total amount withheld from your monthly pay. If too much was withheld, you receive a refund in your December or January payslip. If too little was withheld, you owe the difference and it is deducted.

For most SSW workers employed by the same company for the entire year, the year-end adjustment is invisible — your employer does the calculation, and you may see a small refund or additional deduction on your December payslip without fully understanding why. This is normal and handled on your behalf.

Your employer will ask you to submit a form before year-end: 給与所得者の扶養控除等申告書 (Withholding Exemption Declaration). This form is standard and largely blank for most SSW workers — you fill in your name, address, and basic information. If you have dependants outside Japan, there is a section for that, but the rules are complex and you should ask your company's HR team for guidance. Simply returning the completed form on time is the main thing required of you.

After the year-end adjustment is complete, your employer will give you a 源泉徴収票 (gensen chōshū-hyō, withholding slip) — a one-page document showing your total annual income and the total tax withheld. Keep this document. You will need it if you change jobs, file a tax return, apply for a loan, or prove your income to a government office.

The year-end adjustment handles tax filing for workers employed by a single employer throughout the full calendar year. If your situation falls outside that, you will need to file a 確定申告 (kakutei shinkoku, final tax return) yourself — this is submitted at your local tax office (税務署, zeimusho) between February 16 and March 15 each year for the previous calendar year.

You need to file a 確定申告 if: (1) you changed employers during the year and your previous employer's withholding slip was not submitted to your new employer for the year-end adjustment; (2) you worked for only part of the year and left before your employer completed the year-end adjustment; (3) you had income from multiple sources; or (4) you want to claim a medical expense deduction or a housing loan deduction that your employer cannot process.

Many SSW workers who change employers or leave mid-year are owed a refund — the monthly withholding was calculated assuming a full year of income, and a shorter employment period often means lower actual annual income and therefore lower actual tax. Filing a 確定申告 is how you claim that refund.

The tax return can be filed in person at your local tax office or online via the National Tax Agency's e-Tax system. Tax offices in major cities often have multilingual assistance or interpretation services available during the peak filing season (February–March). Bring your 源泉徴収票 from every employer you worked for during the year, your My Number (individual number) card or notification slip, your residence card, and your bank account details for any refund.

住民税 (jūmin-zei, residence tax) is the tax most likely to surprise SSW workers — because it does not appear at all in your first year in Japan, then arrives as a significant deduction starting in June of your second year.

How it works: residence tax is calculated based on your income from the previous calendar year. In your first calendar year in Japan, you build up a tax liability — but the bill does not come until the following June. Once it starts, it is deducted monthly from your payslip as a flat amount (均等割, kintō-wari) plus a percentage of your prior year's income (所得割, shotoku-wari). For SSW workers earning around ¥3 million annually, the combined residence tax is roughly ¥100,000–¥150,000 per year, or approximately ¥8,000–¥13,000 per month.

This catches many workers off guard: you have been earning ¥220,000 per month net, and then in June of your second year your take-home pay drops by ¥10,000+ because residence tax has now started. You have not done anything wrong — this is the normal billing cycle. The salary calculator on this platform accounts for residence tax in its year-2 estimates.

If you leave Japan before the end of the residence tax billing year (June to May), you may owe a lump sum to your city or ward office. Your employer will typically deduct remaining residence tax from your final payslip. If not resolved before you leave, you may receive a bill at your registered address — if there is no one to receive it, this can lead to complications. Resolve the outstanding residence tax before departure if possible.

The 源泉徴収票 (gensen chōshū-hyō) is a small but important document. It shows your name, your employer's name, your total annual compensation paid, the total income tax withheld, and relevant deduction amounts. It is issued by every employer you work for in Japan.

When you need it: if you change employers, your new employer needs it from your previous employer to complete the year-end adjustment correctly. If you file a 確定申告, you submit it with your return. If you apply for a car loan, credit card, or apartment lease, you may be asked to provide it as proof of income. If you leave Japan permanently and later need to prove your Japanese employment history, it is your main documentary record.

Your employer is legally required to give you your 源泉徴収票 — either in January of the following year after the year-end adjustment, or within one month of leaving if you resign mid-year. If your employer does not give you one, you can request it formally. If they refuse, you can file a complaint with the tax office.

Keep all your 源泉徴収票 documents in a safe place — ideally with your other important documents (residence card, health insurance card, employment contract). They are difficult to replace and you may need them years later.

No income tax deducted on your payslip: if your payslip shows zero income tax, this may indicate your employer is paying you off the books (without proper payroll registration), or using a misclassified employment arrangement to avoid employer obligations. This is a problem for you — not just for your employer — because you are not building a proper tax and social insurance record in Japan.

Employer says you do not need a year-end adjustment or 源泉徴収票: every employer who pays you salary in Japan is legally required to process the year-end adjustment and issue a 源泉徴収票. If yours does not, either they are non-compliant or you are not being classified as an employee. Ask in writing.

Being told residence tax is your problem and you owe a large sum you did not expect: this is not a scam — residence tax is real and often surprises workers in year two. But check that the amount billed matches what you would expect based on your prior year's income. If the amount seems much higher than it should be, contact your city hall's tax department (市税務課) for a breakdown.

Tax deductions for 'training' or 'recruitment': some employers or sending organizations attempt to deduct money from your salary labeling it as training costs or recruitment cost recovery. Under Japan's Labor Standards Act (Article 16), employers cannot enforce penalty contracts or deduct money from wages in advance for speculative future costs. These deductions are illegal regardless of what your contract says.

Not filing 確定申告 when required: if you changed employers and did not file, you may have an outstanding tax liability — or more likely, an unclaimed refund. The statute of limitations for claiming tax refunds in Japan is five years. It is worth checking if you are owed money.