Tax Returns for Agency Workers in Japan: Salary and Freelance Side Jobs

For agency workers with side jobs in Japan, the tax filing test depends on the type and amount of side income, not on agency employment itself. The amount counted toward the ¥200,000 threshold differs between salary from another employer and fees from contracted work.

The following examples and document checklist will help you check whether your main job's year-end adjustment is sufficient. The rules were checked in October 2026.

Separate main-job and side-job payments by contract type

An agency worker's salary is normally paid by the staffing agency that employs them, rather than the company where they are assigned. Obtain the agency's salary withholding slip, and check previous employment documents if you changed agencies during the year.

Side work falls into two broad categories.

• Employment-based side jobs: Part-time employment or work through another staffing agency, generally treated as salary.
• Contracted side work: Writing, design, or other commissioned work, treated as business, miscellaneous, or another income category according to its actual nature.

Contracted-work income is generally revenue minus necessary business expenses. Do not use the same formula to freely subtract commuting costs or personal purchases from salary. Freelance bank deposits also may differ from revenue: where fees or income tax have been deducted, use statements to identify gross revenue and each deduction.

Combine the relevant salary and freelance amounts

These examples assume that all salary is subject to withholding and the main job has undergone year-end adjustment. They exclude separate filing triggers such as annual salary exceeding ¥20 million.

Salary-only side work: use unadjusted gross salary

Annual side-job salary of ¥240,000 generally exceeds the ¥200,000 filing threshold. With ¥180,000, no income other than salary and retirement income, and no other filing requirement, an income tax return may be omitted.

Freelance-only side work: use income after expenses

Revenue of ¥300,000 less necessary expenses of ¥120,000 gives income of ¥180,000, which may qualify for the filing exception available to certain salary earners. With the same revenue but expenses of ¥50,000, income becomes ¥250,000 and generally requires filing.

Both types of side work: add gross salary and freelance income

Part-time salary of ¥120,000 plus freelance revenue of ¥160,000 less ¥60,000 in expenses gives ¥220,000: ¥120,000 plus ¥100,000. The combined amount exceeds ¥200,000 even though each job is below it.

For multiple-employer salary earners, a lower-income exception uses total salary less specified deductions of no more than ¥1.5 million, together with other income of no more than ¥200,000. Basic, medical expense, casualty-loss, and donation deductions are excluded from that calculation. Check the full conditions in the National Tax Agency's salary-earner filing guidance.

The ¥200,000 threshold is not a tax-free allowance. If you file a return to claim medical expense deductions or for another reason, include side income that could otherwise have been omitted under the filing exception.

Year-end adjustment versus a tax return

Year-end adjustment is the employer's settlement of income tax on salary. It normally does not settle tax on freelance income. The treatment of another employer's salary also depends on whether it was earned concurrently as a side job or came from a previous job you left.

Do not assume that submitting a previous employer's withholding slip means every side job was covered. Ask your staffing agency which salary amounts were included. If you changed jobs within the year, check for missing or duplicated documents.

Documents to gather

Salary documents

Collect withholding slips for the main and side jobs. Relevant figures include gross payment amounts, withheld tax, and social insurance payments. Payslips and bank histories alone may not provide all year-end adjustment information.

A salary withholding slip supplies information for preparing the return. That is distinct from whether a document must be physically attached to a paper return. Follow the instructions for your filing method.

Contracted-work documents

• Invoices, transaction statements, revenue ledgers, and other records showing revenue.
• Receipts and statements supporting necessary business expenses.
• Statements showing tax withheld from fees, where applicable.
• Evidence for deductions you claim, such as life-insurance premium deductions.

A payment statement, or shiharai chosho, can help reconcile figures, but the payer is not always required to provide one to the recipient. You do not have to wait for it before preparing a return; total your own books and transaction records. For expenses shared between personal and business use, keep records explaining the business-use portion.

Can you choose to pay resident tax yourself on salary too?

A resident tax declaration may be required even if an income tax return can be omitted. Conversely, a separate municipal declaration can be unnecessary where salary payment reports have been submitted and there is no other income. Check your municipality's guidance.

The resident tax collection-method choice on an income tax return concerns income other than salary and public pensions. It does not let you freely choose self-payment for every source, including side-job salary, and does not guarantee that your employer will not learn about side work. Ask your municipality about salary treatment; Yokohama City's guidance on payroll collection is one example.

Before starting side work, also check the staffing agency's employment rules and notification process. Tax filing and the employer's side-work rules are separate procedures.

Four steps to prepare your return

1. List main-job and side-job salary separately from contracted-work revenue and expenses.
2. Gather the relevant year's withholding slips and deduction records, and confirm what was covered by year-end adjustment.
3. Use the correct year's National Tax Agency Tax Return Preparation Corner to check the return and tax calculation.
4. Complete required filing and payment, then retain submitted data and supporting records. Check resident tax even if no income tax return is filed.

For frequent short-term salary work, see the spot-work tax guide. If you are starting freelance work, see how to find contracted projects. Keeping monthly records reduces the effort of reconstructing several jobs at year-end.