Side Job Tax Filing in Japan: Everything You Need to Know

Japan's side job (fukugyo) economy is booming. Remote work has made it easier than ever to freelance, consult, or sell on platforms like Mercari after hours. But with side income comes a critical question: when do you need to file a tax return (kakutei shinkoku)?

The short answer: if your net side income exceeds 200,000 yen per year, you must file. But the full picture is more nuanced — and the 2025 basic deduction increase to 950,000 yen has changed the math for many workers.

The 200,000 Yen Rule

If your net side income (revenue minus expenses) exceeds 200,000 yen in a calendar year, you are required to file an income tax return.

Condition	Income Tax Return Required?
Side income ≤ ¥200,000	Generally no
Side income > ¥200,000	Yes
Claiming medical expense deduction	Yes, even if under ¥200,000

Critical exception: Even if your side income is under 200,000 yen, you must still file a resident tax (juminzei) return with your municipal office. The 200,000 yen rule only applies to national income tax.

2025 Tax Change: Basic Deduction Increase

Starting 2025, the basic deduction (kiso kojo) increased from ¥480,000 to ¥950,000. Combined with the employment income deduction (¥550,000), workers can earn up to ¥1,500,000 before paying income tax.

Impact on Side Workers

• More side income may fall within the tax-free range
• Social insurance dependent status (¥1,300,000 wall) remains separate
• Those with both employment and side income benefit most

Miscellaneous Income vs Business Income

Side income must be classified as either miscellaneous income (zatsu shotoku) or business income (jigyo shotoku).

Factor	Miscellaneous Income	Business Income
Scope	Occasional side work	Continuous, independent business
Blue return	Not eligible	Eligible (up to ¥650,000 deduction)
Loss offset	Cannot offset against salary	Can offset against salary income
Bookkeeping	Simple records	Formal double-entry bookkeeping

When Does Side Income Qualify as Business Income?

• Regular, repeated income generation
• Conducted as an independent business
• Significant time and effort invested
• Proper bookkeeping maintained
• Business registration (kaigyo todoke) filed

Blue Return vs White Return

Blue Return (Ao-iro Shinkoku) Benefits

Benefit	Details
Special deduction	Up to ¥650,000 (with e-Tax filing)
Loss carryforward	Carry losses forward for 3 years
Family employee salaries	Deductible as business expenses
Small asset expensing	Assets under ¥300,000 fully expensed

Blue Return Requirements

1. Income classified as business income (not miscellaneous)
2. Business registration filed with tax office
3. Blue return approval application submitted on time
4. Double-entry bookkeeping maintained

Deductible Expenses

Category	Examples
Communication	Internet, phone (proportional)
Supplies	Stationery, peripherals
Transportation	Client meeting travel costs
Books & training	Business-related books, seminars
Depreciation	Computer, camera (proportional)
Rent (proportional)	Home office portion of rent

Key: Maintain clear records of the business-to-personal ratio (kaji anbun) for any shared expenses.

Resident Tax: Required Even Under ¥200,000

Item	Income Tax	Resident Tax
¥200,000 rule	Applies	Does NOT apply (declare from ¥1)
Filed with	Tax office	Municipal office
Method	e-Tax or paper	Municipal office counter

Tip: Choose "futsuu choshu" (ordinary collection) for resident tax so your side income tax isn't deducted from your company paycheck — keeping your side job private from your employer.

Filing Process

Filing Period

February 16 to March 15 each year (next business day if weekend/holiday).

Filing Methods

1. e-Tax: Online using My Number Card + smartphone/PC. Required for the full ¥650,000 blue return deduction.
2. In person: Submit at your local tax office.
3. By mail: Postmark date counts.

Required Documents

• Withholding tax certificate (gensen choshuhyo) from employer
• Income and expense statement or blue return financial statements
• My Number verification
• Expense receipts and invoices

Sharing Tax Documents Securely

When sharing financial documents with your accountant or tax advisor, sending them via iMessage or email creates security risks — especially documents containing income details, My Number information, and bank account numbers.

LOCK.PUB lets you create password-protected links to share sensitive tax information. Set an expiration date so access automatically revokes after filing season.

Common Questions

What happens if I don't file?

Penalties include late payment tax (7.3%–14.6% annually) and failure-to-file surcharge (15%–20%).

Can I keep my side job hidden from my employer?

Selecting "ordinary collection" for resident tax prevents side income tax from appearing on your company payroll. However, this isn't 100% guaranteed.

Can I use furusato nozei (hometown tax)?

Yes, but you cannot use the one-stop exception — you must claim it through your tax return.

Summary

Filing taxes on side income isn't as intimidating as it seems. Know the 200,000 yen rule, understand the miscellaneous vs business income distinction, track your expenses carefully, and consider the blue return if you qualify.

For sharing tax documents securely with your accountant, try LOCK.PUB's password-protected links with automatic expiration.