📄 Japan Year-End Adjustment Calculator

The Japan Year-End Tax Adjustment Calculator estimates the outcome of your nenmatsu chosei (年末調整), the year-end income tax reconciliation that most Japanese companies perform in December. This process compares the total income tax withheld from your salary throughout the year with your actual annual tax liability.

Throughout the year, your employer withholds estimated income tax from each paycheck using a simplified monthly formula. This formula cannot account for mid-year changes or special deductions. At year-end, the company recalculates your actual annual tax using the full progressive bracket system and all applicable deductions:

• Employment income deduction (kyuyo shotoku kojo) — based on total annual salary
• Basic deduction (shotoku kojo) — 480,000 yen for standard taxpayers
• Dependent deductions (fuyo kojo) — for spouses, children, and parents
• Social insurance deduction (shakai hokenryo kojo) — total annual premiums
• Medical expense deduction (iryohi kojo) — medical expenses over 100,000 yen
• Life insurance deduction (seiho kojo) — for qualifying insurance premiums
• Housing loan deduction (jutaku kashi kojo) — for mortgage holders (first 13 years)
• Spouse special deduction (haigusha special kojo) — for working spouses

If your actual annual tax is less than what was withheld, you receive a refund (kanpu) on your December or January payslip. If more tax was due, you pay the difference (tsuika choshu) through a deduction from your December salary.

The calculator follows the nenmatsu chosei process:

Step 1: Calculate total annual gross salary (12 months + bonuses)

Step 2: Apply employment income deduction to get employment income (kyuyo shotoku)

Step 3: Subtract all applicable deductions (social insurance, basic, dependent, medical, insurance, housing)

Step 4: Apply progressive tax brackets (5%-45%) plus 2.1% reconstruction surcharge

Step 5: Compare with total tax withheld from monthly salary and bonuses

Positive result = refund (kanpu). Negative result = additional withholding (tsuika choshu).

1. Enter your total annual gross salary (including bonuses).
2. Enter total income tax withheld this year (from your payslips).
3. Add the number of dependents claimed.
4. Enter estimated deductions (medical, insurance, housing, etc.).
5. Click Calculate to see your expected refund or additional tax.

What is nenmatsu chosei (year-end tax adjustment)?

Nenmatsu chosei is the annual reconciliation of income tax performed by your employer in December. Throughout the year, tax is withheld from each paycheck using an estimated formula. At year-end, the company recalculates your actual annual tax liability using the full progressive bracket system and all deductions. If too much was withheld, you get a refund (kanpu) in your December or January salary.

What happens if I miss the nenmatsu chosei submission deadline?

If you miss the company deadline for submitting deduction forms, you must file a final tax return (kakutei shinkoku / 確定申告) yourself during the tax filing period (mid-February to mid-March). You can still claim all the same deductions, but you must handle the paperwork independently. The refund would be deposited to your bank account after processing.

What deductions are available only at year-end adjustment?

The main deductions applied at nenmatsu chosei include: medical expense deduction (iryo hi kojo), life insurance deduction (seimei hoken kojo), earthquake insurance deduction, housing loan deduction (jutaku kashi kojo), spouse special deduction, dependent deductions, iDeCo pension contributions, and small business mutual aid premiums. Some of these require specific documentation.

Will I get a refund or owe more tax at year-end?

Most salaried workers receive a small refund (5,000-50,000 yen) because the monthly withholding slightly over-collects. Larger refunds come from deductions like medical expenses, housing loan, and insurance premiums. High earners (10+ million yen) may owe additional tax because monthly withholding under-collects at higher brackets. This calculator helps estimate which scenario applies to you.

What is the difference between nenmatsu chosei and kakutei shinkoku?

Nenmatsu chosei (year-end adjustment) is performed by your employer automatically in December for all standard employees. Kakutei shinkoku (final tax return) is self-filed between February and March, required for self-employed, those with side income over 200,000 yen, those who missed nenmatsu chosei, or those claiming deductions not handled by the employer (like furusato nozei beyond the one-stop system).

This tool is for informational purposes only and does not constitute financial advice. Consult a qualified financial professional for advice specific to your situation.

Submit your deduction claims by December: Companies typically require deduction forms (chosei shinseisho) to be submitted by late November or early December. Missing the deadline means you must file a final tax return (kakutei shinkoku) yourself between February and March of the following year.

Medical expense deduction threshold: You can deduct the medical expenses that exceed the lower of 100,000 yen or 5% of your total income (this tool applies the 100,000 yen floor), capped at 2,000,000 yen per year. This includes dental work, fertility treatments, over-the-counter medicine (partially), and transportation to hospitals. Keep all receipts. Use our calculator to estimate the deduction impact.

Housing loan deduction is significant: For mortgages taken after 2019, the deduction can be up to 400,000 yen per year for up to 13 years (varies by property type, move-in year and loan balance). This is often the largest single deduction for homeowners. If you bought a house this year, make sure to submit the required certificates.

iDeCo contributions reduce taxable income: If you contribute to iDeCo (individual-type defined contribution pension), the full contribution amount is deducted from taxable income. This is applied at year-end adjustment. The maximum monthly contribution varies by employment type.