How to manage expenses and file taxes for side income without employer discovery.
For general reference only. Consult a tax professional for individual advice. Last verified: January 1, 2026 · Source: 国税庁
This is an expense management guide for those working full-time while having a side job. Properly claiming expenses provides tax benefits, but also understand key points to maintain privacy from your employer.
For salary earners, if side income exceeds ¥200,000/year, tax filing is required. However, residence tax filing is required even under ¥200,000.
By selecting "Self Payment" in the residence tax section of your tax return, your side income tax will not be notified to your employer.
Check if side jobs are prohibited. If permission is required, consider applying formally.
Side jobs competing with your main job may violate regulations. Also avoid using main job information.
Even if side income is under ¥200,000/year, residence tax filing is required. File with your local municipality even if income tax filing is not needed.
Tip: Prorate by business use if shared. Under ¥100k is immediate expense, Blue Return allows up to ¥300k.
Tip: If working from home, prorate by floor area. Typically 20-40% is common.
Tip: If shared between business and personal, prorate by call logs or usage time. Typically 30-50%.
Tip: Relevance to your side job is key. Fully deductible if you can explain the business connection.
If you don't select "Self Payment" in the residence tax section of your tax return, your employer will be notified.
Instantly check if an expense is deductible. Free tool that shows categories and deduction rates.
Denpyo scans your receipts and finds tax savings automatically.
