Year-end adjustment vs a final tax return
What each one covers, who performs it, and when you still need to file despite year-end adjustment.
Year-end adjustment (年末調整) is your employer reconciling the income tax on the salary they paid; a final return (確定申告) is you reconciling all reportable income — you may need the return for side income, medical expenses, or the first mortgage-credit year even after year-end adjustment.
Effective: 2026-01-01 to 2026-12-31
Professional review pending — treat as draft and confirm with the authorities.
Key points
- Year-end adjustment is done by the employer; a final return is done by you (or a 税理士).
- Year-end adjustment covers only employment income that employer handled.
- Medical expense deduction, donations beyond one-stop, and the first mortgage-credit year need a return.
- A year-end adjustment does not cure unreported side, rental, overseas, or investment income.
Who does each, and what it covers
Your employer runs year-end adjustment as part of payroll near year-end. It typically applies the basic, spouse, dependent, social-insurance, and life-insurance deductions, and — from the second year — the mortgage credit. A final return, filed by you ordinarily between February 16 and March 15, covers everything: business and rental results, capital gains, the medical and donation deductions, the first mortgage-credit year, and the foreign-tax credit.
When both are involved
You can be adjusted and still have to file. A salaried employee with more than ¥200,000 of side income, two jobs, large medical bills, or a first-year mortgage files a return that starts from the withholding certificate the employer already produced. Neither process is a universal cure: resident-tax declarations, gift tax, and consumption tax can remain separate obligations.
Who this is for
- Employees unsure whether they must file
- People who missed year-end adjustment (left a job)
What this is not
- Freelancers with no employment income
- If you left a job before year-end and no employer adjusted you, you likely need a return to claim a refund.
Frequently asked questions
Do I need to file a tax return in Japan?
Many employees do not, because tax is settled by year-end adjustment (年末調整). You generally must file (確定申告) if you have side income over ¥200,000, two or more employers, self-employment income, sizeable investment or crypto gains, or you want to claim deductions like large medical costs or a first-year mortgage credit. Filing season is Feb 16 – Mar 15 via e-Tax. When unsure, check the NTA guidance or ask a 税理士.