【summary】
In principle, even company employees are required to file a tax return in the year they receive the mortgage deduction for the first time.
If you think that the year-end adjustment is all you need to do, you may miss out on deductions.
This article summarizes the general flow as of June 2026. Required documents and deduction details for home loan deductions vary depending on move-in period, housing performance, floor area, income, loan period, availability of subsidies, etc.
The first step to check is as follows.
| Steps | What to do |
|---|---|
| 1 | Check if you are eligible for home loan deduction |
| 2 | Prepare year-end balance certificate, registration certificate, etc. |
| 3 | Enter at the National Tax Agency's tax return preparation corner |
| 4 | Attach/send or submit required documents |
| 5 | Confirm refund transfer |
From the second year onward, company employees may be able to complete the year-end adjustment procedure.
However, be sure to prepare early so you don't forget the first year.
What is home loan deduction?
Home loan deduction is a system that allows you to receive a deduction from your income tax if you meet certain requirements, such as when you acquire a home using a home loan.
Officially, it is called special deduction for housing loans, etc.
The National Tax Agency advises that if you are receiving a mortgage deduction for the first time, you will need to file a final tax return with the documents appropriate to your housing category attached.
The detailed requirements of the system vary depending on the type of housing, move-in period, floor area, income, loan period, energy-saving performance, etc.
People who need to file a tax return in the first year
Even company employees are required to file a tax return in the first year of the mortgage deduction.
| People | Treatment of the first year |
|---|---|
| Company employee | In principle, final tax return is required |
| Self-employed | Procedures with final tax return |
| Pair loan with both parents | Each person may need to file a declaration |
| Joint and several debts | Check equity and burden ratio |
| People who have changed jobs | Be careful when preparing the withholding tax slip |
It's best not to think that because you're an office worker, you'll automatically go back after the year-end adjustment.
You will need to move on your own for the first year.
Examples of required documents
Required documents vary depending on the type of housing and acquisition method.
Typically, we will check the following documents:
| Documents | Where to check |
|---|---|
| Withholding tax slip | Work place |
| Year-end mortgage balance certificate | Financial institution |
| Certificate of Registration | Legal Affairs Bureau |
| Sales contract/construction contract | Real estate company, construction company |
| Documents showing the amount of subsidies, etc. | Local governments, businesses |
| Documents showing housing performance | Required depending on the type of housing |
If you do not have all the documents, you may be able to enter the information but it will stop at the declaration stage.
It's easier to organize your documents in a file after you move in than to collect them just before the tax return period.
Step 1. Check target requirements
First, check whether you are eligible for home loan deduction.
| Check items | Contents |
|---|---|
| When did you move in | When did you start living |
| Borrowing period | Mortgage repayment period |
| Floor space | Does it meet the requirements |
| Income | Is it subject to income restrictions? |
| Housing classification | Newly built, used, certified homes, energy-saving homes, etc. |
The mortgage deduction is not a system that anyone can automatically receive by purchasing a home.
Before signing a contract, it is best to check with your real estate company, tax accountant, or National Tax Agency information to see if you are eligible.
Step 2. Enter information at the tax return preparation corner
If you use the National Tax Agency's tax return preparation corner, you can create your tax return by following the on-screen instructions.
For housing loan deduction, enter the year-end balance of borrowings, acquisition price, floor area, start date of residence, etc.
The problem here is where to enter the numbers on the contract or registration certificate.
Gathering the required documents on your desk before entering data will make it harder to stop working.
Step 3. Submit by e-Tax or in writing
The return can be submitted by e-Tax or in writing.
| Method | Features |
|---|---|
| e-Tax | Can be sent from home |
| Document submission | Bring or mail to tax office |
| Consultation with the tax office | You can proceed while checking any unclear points |
In some cases, you may be able to file a tax return using your My Number card or smartphone.
However, there are many items to fill in for your first home loan deduction, so please allow plenty of time.
Flow from 2nd year onwards
If you are a company employee, you may be able to receive a mortgage deduction during the year-end adjustment from the second year onwards.
Submit the deduction form sent from the tax office and the year-end balance certificate sent from your financial institution to your workplace.
| Year | Procedures |
|---|---|
| First year | Tax return |
| From 2nd year onward | May be possible through year-end adjustment |
Even after the second year, be careful not to lose your documents.
It's a good idea to create a folder for mortgage deductions so you don't panic during the year-end adjustment period.
Points to note regarding pair loans/joint debts
For pair loans and joint debts, declaration is a little more complicated.
| Case | Points to note |
|---|---|
| Pair loan | Each husband and wife may declare themselves as loan holders |
| Joint and several debts | Check equity, burden ratio, and proportionate share of year-end balance |
| One partner is on childcare leave | The income tax amount may be small and not enough to be deducted |
| Financial burden that looks like a gift | Be careful of the discrepancy between equity and payment |
Rather than proceeding with your own judgment, it is safer to check with the tax office, financial institution, real estate company, and, if necessary, a tax accountant.
summary
If you forget to file your first year's tax return, you may miss out on the mortgage deduction.
Even if you are a company employee, you should consider filing your own tax return for the first year.
It is important to collect the necessary documents as early as possible, fill them out at the National Tax Agency's tax return preparation corner, and submit them within the deadline.
In the case of a pair loan or joint debt, the equity and burden ratio are also involved, so be sure to check this early.
Please note that the amount of deduction and required documents will change depending on system revisions and housing classification. Before actually filing your tax return, please check the latest page of the National Tax Agency, your tax office, or a tax accountant.
Reference
- National Tax Agency "For those receiving home loan deduction"
- National Tax Agency "Land/Buildings (mortgage deduction, etc.)"