How to File a Tax Return for a Side Job as Temp Staff

Are you wondering, "I've started a side job while working as a temp staff, but how should I handle my tax return?" A temp staff worker's pay counts as employment income, and it's common to have the year-end adjustment done by the staffing agency. On the other hand, your side job income may require you to file a tax return yourself, and the judgment and calculation change depending on the type of side job. This article explains how to file a tax return when you have a side job as temp staff, broken down by the type of side job.

Do temp staff need to file a tax return when they have a side job? The basics

A temp staff worker's pay is "employment income," and your main staffing agency performs the year-end adjustment and settles your income tax. However, the year-end adjustment can only be done for one company's worth of income. Because income earned from a side job is outside the scope of the year-end adjustment, in principle you need to file a tax return yourself to settle it.

The benchmark is the "200,000 yen rule." For temp staff who have received a year-end adjustment, a tax return is required if your side job income (or salary income) exceeds 200,000 yen per year. If it is 200,000 yen or less, an income tax return is in principle not required, but a residence tax filing is separately required (explained later).

The tax return changes depending on the type of side job

The most important point when thinking about a tax return for a temp staff side job is whether the side job is "salary" or "non-salary (such as contract work)." The judgment criteria and the calculation change depending on the type.

When the side job is also salary (a part-time job, another temp assignment, etc.)

When your side job is salary, such as another part-time job or temp assignment, that side job's pay becomes "secondary salary." Since the year-end adjustment can only be done at one main staffing agency, a tax return is required if your side job's salary income exceeds 200,000 yen per year. You prepare both withholding slips and file by combining them.

When the side job is contract work or remote work (miscellaneous income or business income)

Side job income earned through contract work, such as crowdsourcing or remote work, becomes "miscellaneous income" or "business income." In this case, a tax return is required if your "income" after subtracting expenses from your revenue exceeds 200,000 yen per year. Unlike salary, a feature is that you can record expenses.

When you hold multiple temp assignments (several staffing agencies)

When you work at several staffing agencies, the year-end adjustment can be done at only one of them (your primary salary). Because the pay from the other staffing agencies is not adjusted at year-end, you gather all the withholding slips, file a tax return, and calculate the correct tax amount.

Cases where a temp staff side job needs a tax return, and cases where it doesn't

Organizing the basic judgment, it works out as follows.

• Side job is salary: a tax return is required if the side job's salary income exceeds 200,000 yen per year
• Side job is contract work, etc.: a tax return is required if income (revenue minus expenses) exceeds 200,000 yen per year
• 200,000 yen or less: an income tax return is in principle not required (but a residence tax filing is separately required)
• If you want to claim a medical expense deduction or hometown tax donation, or too much was withheld at source: filing may result in a refund

What you need for a temp staff side job tax return

If you are filing, prepare the following documents according to the type of side job.

• The withholding slip from your staffing agency (main job)
• If the side job is salary: the withholding slip from the side job
• If the side job is contract work: the payment record, or your own record of revenue and expenses, and receipts for expenses
• My Number card (or notification card plus identity verification documents)
• If claiming deductions, the relevant deduction certificates (such as medical expense statements)

You can complete the preparation and submission of the tax return from home using the National Tax Agency's "Tax Return Preparation Corner" or e-Tax. For the specific procedure and the difference between blue and white returns, our article on the side job tax return guide explains it in detail with diagrams.

Points to watch when filing a tax return for a temp staff side job

• Even at 200,000 yen or less, a residence tax filing is separately required (the income tax 200,000 yen rule does not apply to residence tax)
• If you don't want your side job known through the residence tax notice, check whether you can choose ordinary collection (paying it yourself) (see our article on residence tax measures too)
• If you work within a dependent's limit, manage your income so you don't exceed the "walls" such as 1.03 million yen and the 1.3 million yen social insurance threshold
• Withholding slips and payment records are essential for filing, so keep them safe
• Before starting a side job, check whether side jobs are permitted under the staffing agency's work rules
• If a tax return is required and you don't file, you may be charged an additional tax for non-filing or a late payment penalty

FAQ about tax returns for temp staff side jobs

Q. If my temp staff side job is 200,000 yen or less, can I skip the tax return?

For temp staff who have received a year-end adjustment, if your side job income (or revenue in the case of salary) is 200,000 yen or less, an income tax return is in principle not required. However, a residence tax filing is separately required, so don't forget to file with your local municipality.

Q. If I hold multiple temp assignments, do I need to file a tax return?

Since the year-end adjustment can only be done at one company, a tax return is required if the pay from your other staffing agencies exceeds 200,000 yen per year. You file by combining all the withholding slips. For general points on holding multiple jobs (double work), please also refer to our article on double work.

Q. If I file a tax return, will my side job be found out by the staffing agency?

There is a possibility of it being known through the residence tax notice, but if you can choose ordinary collection (paying it yourself) when filing your tax return or residence tax, you can lower the risk. For details, please see our article on how to keep a side job from being found out.

Summary: File a temp staff side job tax return according to the type

When you have a side job as temp staff, your staffing agency's pay is adjusted at year-end, and you file the side job portion yourself as the basic approach. If the side job is salary, a tax return is required when revenue exceeds 200,000 yen per year; if it is contract work, when income after subtracting expenses exceeds that. Note that even at 200,000 yen or less, a residence tax filing is required, so prepare documents such as withholding slips and proceed with filing early as needed.

* The tax amount and whether filing is required differ depending on your individual situation. If you are unsure, we recommend consulting your local tax office or a tax accountant.