Year-End Tax Settlement Correction Claims: 5-Year Deadline and Refund Application Process

If you paid too much income tax because you missed a deduction or tax reduction during your year-end tax settlement, you can request that the tax amount be recalculated by filing a claim for reassessment. However, the deadline is not uniformly May 31 of the following year for all employees. The starting date of the five-year period may differ depending on whether your tax liability was finalized through the year-end tax settlement or you separately filed a final global income tax return.

What Is a Claim for Reassessment?

A claim for reassessment is a system under which a taxpayer may ask the head of the competent tax office to reduce a previously reported or finalized tax base and tax amount when they exceed the correct amounts. Employees who paid too much income tax because they omitted a deduction, tax credit, or tax reduction during their year-end tax settlement may also use this system.

Common examples include:

• You did not submit the documents required for the monthly rent tax credit to your employer.
• You later discovered medical expenses omitted from the simplified year-end tax settlement service.
• You obtained a receipt for a qualifying donation after the fact.
• You failed to apply for the income tax reduction for employees of small and medium-sized enterprises.
• You did not claim a dependent deduction even though the requirements were met for that year.
• You omitted a temporary tax credit applicable to that year, such as a marriage-related tax credit.

A claim for reassessment is not a procedure for applying for a new benefit. It is a procedure for correcting taxes by proving expenses and requirements that had already been met in the relevant tax year. Current deduction requirements cannot be applied retroactively to past years.

How to Calculate the Five-Year Deadline

Under the Framework Act on National Taxes, the general deadline for filing a claim for reassessment is within five years after the statutory filing deadline. However, for a person whose tax liability was finalized through the year-end settlement of wage and salary income, the payment deadline for the year-end settlement tax and related dates may serve as the reference date.

If You Only Completed a Year-End Tax Settlement

If you had only wage and salary income and did not separately file a final global income tax return, the five-year period is generally calculated from the payment deadline for the year-end settlement tax. Under a standard schedule, March 10 of the following year serves as the reference date. However, if the filing of the statement of payment or the payment of tax differs from the usual circumstances, you should confirm the deadline with the tax office.

For example, if you completed only a year-end tax settlement for wage and salary income attributable to 2021, the general deadline for a claim for reassessment may be regarded as March 10, 2027.

If You Filed a Final Global Income Tax Return

If you filed a final global income tax return for the income of the relevant year after completing the year-end tax settlement, the deadline for a claim for reassessment is calculated from the statutory deadline for that return. The statutory filing deadline is generally May 31 of the following year.

Therefore, if you reported income attributable to 2021 through a global income tax return in May 2022, you can generally file a claim for reassessment by May 31, 2027.

The actual deadline may differ depending on holiday-related deadline adjustments, filing history, whether a statement of payment was submitted, and other factors. If the deadline is approaching, it is safest to review your filing history for the relevant year on Hometax or ask the competent tax office for the exact deadline.

For income attributable to 2020, the five-year period expired in 2026 under both the year-end tax settlement standard and the standard global income tax filing deadline. However, if a subsequent event that could not have been anticipated at the time of filing has occurred, such as the finalization of a court judgment, a special rule separate from an ordinary claim for reassessment may apply, so the individual circumstances should be reviewed.

Should You File in March or May?

March 10 of the following year is generally associated with an employer’s schedule for paying taxes related to year-end tax settlements and submitting statements of payment. Employees can view materials for a claim for reassessment on Hometax after the employer submits the statement of payment.

If the final global income tax filing period in May of the following year has not yet ended, the usual method is to file a wage and salary income return that reflects the omitted deductions. After the statutory filing deadline has passed, use the claim for reassessment procedure.

Deductions and Supporting Documents to Check Before Applying

Monthly Rent Tax Credit

To claim the monthly rent tax credit, you must be able to verify the lease agreement and actual payment history. The following documents are generally required:

• Resident registration certificate
• Copy of the lease agreement
• Records showing payment of monthly rent to the landlord, such as bank transfer records or deposit receipts

The laws and regulations applicable to each tax year govern specific requirements and credit rates, including total salary, home size or standard market value, homeownership status, and change of address. The credit is not granted solely because you paid monthly rent.

Medical Expense Tax Credit

For medical expenses not shown in the simplified year-end tax settlement data, you may obtain and submit receipts from the medical institution. However, not all non-covered medical expenses excluded from national health insurance coverage are deductible. Because the law excludes certain items, such as expenses for cosmetic or plastic surgery or health improvement purposes, you must confirm whether the expense was for treatment and qualifies for the credit.

Donation Tax Credit

A donation receipt issued by a qualifying organization is required. If you made a payment to a religious or nonprofit organization, you must also confirm whether the organization qualifies for a deduction under tax law. A simple bank transfer record may not be sufficient for the donation tax credit.

Income Tax Reduction for Employees of Small and Medium-Sized Enterprises

The tax reduction for employees of small and medium-sized enterprises does not automatically apply to all employees of such companies. All requirements must be met, including the employee’s age and work experience, the company’s industry, the employment date, and the reduction period. The reduction is not confirmed merely because the employer is a small or medium-sized enterprise.

Dependent-Related Deductions

You must verify the dependent’s income amount, age, and livelihood requirements, as well as whether another family member has claimed a duplicate deduction. If two people claim the same dependent at the same time, additional tax may instead become payable.

Hometax Claim for Reassessment Procedure

The Hometax interface and menu names may change, but the general procedure is as follows:

1. Log in to Hometax using identity verification.
2. Go to the menu related to Tax Filing > Global Income Tax Return > Wage and Salary Income Return > Claim for Reassessment.
3. Select the relevant tax year for the claim for reassessment.
4. Import the wage and salary income statement of payment submitted by your employer and the existing deduction details.
5. Enter the omitted income deductions, tax credits, and tax reductions.
6. Attach supporting documents such as the lease agreement, transfer records, and receipts.
7. Confirm the account for receiving the refund and your contact information, then submit the claim.
8. Check the filing and claim history on Hometax for the receipt result and processing status.

An employee may file a claim directly without going through the employer. However, if the statement of payment cannot be retrieved or the filing structure is complex, you may submit the claim in writing to the competent tax office or have it reviewed by a tax professional.

Processing After Submission and Local Income Tax

The tax office reviews the claim and supporting documents to decide whether to reduce the tax amount. Under the Framework Act on National Taxes, the head of the tax office that receives a claim for reassessment must, in principle, make a decision or notify the claimant of the result within two months from the filing date. However, the actual timing of the refund may differ depending on verification of the facts or requests for supplementary materials.

If income tax is reduced, the associated individual local income tax may also change. Confirm whether the national tax refund result is transmitted to the local government. If necessary, separately check the local income tax refund or reassessment procedure through Wetax or the competent local government.

Common Mistakes

• Do not assume that May 31 is the deadline for every employee. A different reference date may apply to a person who completed only a year-end tax settlement.
• Do not apply current deduction requirements to past years. A claim for reassessment is reviewed under the laws and regulations in effect for each relevant tax year.
• Do not treat all non-covered medical expenses as eligible for a credit. You must verify the treatment purpose and the items excluded by law.
• Do not determine eligibility for a tax reduction or donation credit based only on the name of a company or organization. You must provide evidence that it qualifies under the law.
• Do not treat the estimated refund as a confirmed amount. The actual refund varies depending on the previously determined tax amount, withholding tax, and deduction limits.
• Do not use a claim for reassessment to address omitted income. If you underreported tax, you should consider another procedure, such as filing an amended return.

Key Takeaways

A claim for reassessment allows you to correct deductions and tax reductions missed during a year-end tax settlement, but the right to file a claim does not remain available indefinitely. If you completed only a year-end tax settlement, calculate the five-year period based on the payment deadline for the year-end settlement tax and related dates. If you also filed a global income tax return, calculate it based on the statutory filing deadline for that return.

Before applying, first review your filing history and the applicable laws and regulations for each relevant tax year. The correct next step is to prepare lease agreements, receipts, transfer records, and other documents proving that you met the deduction requirements, and then submit them through Hometax.