[Summary]
When starting a side business, the first thing to worry about is expenses. However, if you only think about expenses in terms of whether they can be cut, it can be dangerous.
Consider expenses for your side job based on whether they were necessary to earn that income. Items that are used for both personal and personal purposes must be divided reasonably according to the proportion used for work.
In this article, we will organize the points that beginners should check first in the order in which they are most likely to stumble in practice. Since taxes vary depending on individual circumstances, please confirm the final decision with an official or specialized contact such as the National Tax Agency, local government, tax office, or tax accountant.
First, the conclusion
Consider expenses for your side job based on whether they were necessary to earn that income. Items that are used for both personal and personal purposes must be divided reasonably according to the proportion used for work.
| Check points | way of seeing |
|---|---|
| Easy to understand expenses | Server fees, business tools, outsourcing fees, interview transportation expenses, etc. |
| Proration is required | Smartphone bills, rent, electricity bills, communication costs, etc. |
| difficult expenses | Personal eating and drinking, hobbies, family use, unexplained purchases. |
| evidence | Receipts, details, purpose of use notes. |
The important thing when reading tax articles is not just memorizing the system name. It's about looking at your income, accounts, deductions, and reporting methods separately.
common misconceptions
- Anything with a receipt is considered an expense.
- There is no basis for apportioning housework.
- Include expenses that are not related to your side job.
This is an area where it is easy to get confused just by reading the search article. In particular, "sales" and "income," "income tax" and "resident tax," and "NISA" and "taxable account" need to be treated as different things.
Order of actual checking
If you are confused, it will be easier to organize if you check them in the following order.
- Can you explain the relationship with income?
- Did you exclude personal use?
- Did you save your receipt?
- Do you record it every month?
If it is still difficult to make a decision after looking at the above, it is safer not to leave it to your own judgment. Please check through official channels such as consultation with the tax office, the National Tax Agency's tax return preparation corner, and consultation with a tax accountant.
Summary
Rather than attacking expenses, it is important to leave them in a way that can be explained. Make a record that you can look at later and be satisfied with.
While it's hard to get away with not knowing about taxes, there's no need to fear them too much if you sort them out early. When your income increases, when you start investing, or when you want to use deductions, it is most practical to prepare your records early rather than at the end of the year.
Source/reference materials
- National Tax Agency, No.2210 Easy knowledge of necessary expenses
- Confirmation date: 2026-05-30