Framework Act on National Taxes — Three Ways to Fix a Return, and Refunds

Articles are cited from the version in force on 11 August 2026 (Act No. 21860), checked on 20 September 2026.

Three ways to fix a return

Suppose you discover a mistake after filing. What to do depends on which way the mistake runs.

Why the split? A correction in the state’s favour can be made by the taxpayer alone; one against the state goes through the authority’s judgment. There is no reason to stop someone who wants to pay more, but a request for money back requires the facts to be checked. That is why a taxpayer “may file” an amended return but “may request” a correction.

Amended returns (Article 45)

Those who filed a tax base return by the statutory deadline and those who filed a return after the deadline are eligible. The deadline is before the head of the competent tax office determines or corrects and gives notice, and before the assessment exclusion period under Article 26-2 expires.

Both conditions apply at once. Even with time left in the exclusion period, once notice has been received an amended return is no longer possible. A taxpayer cannot step into a matter the authority has already taken up.

There are three grounds: tax was understated; losses or refund amounts were overstated; or the return was otherwise incomplete in ways set by presidential decree, such as omitted withholding settlements or tax adjustments. The third ground carries a proviso: cases in which a request for correction can be made are excluded, which stops the two procedures from overlapping.

The sooner, the bigger the reduction (Article 48(2)1)

Here lies the practical benefit of an amended return: the under-reporting penalty tax (Article 47-3) is reduced depending on timing.

Beyond two years there is no reduction. And an amended return filed knowing in advance that the tax base and tax would be corrected is excluded from the reduction. Rushing to file after receiving notice of an audit is not voluntary correction.

Requests for correction (Article 45-2)

Two different periods attach to different grounds.

Ordinary request for correction — 5 years (paragraph 1)

The request is made within five years after the statutory filing deadline, on two grounds:

• the tax base or tax reported exceeds what should have been reported; or
• the losses, tax credits or refund amounts reported fall short of what should have been reported.

It is the mirror image of the grounds for an amended return.

There is one proviso. For a tax base or tax increased by a determination or correction, the request must be made within three months of learning of the disposition (and still within five years of the statutory filing deadline).

Subsequent-event request for correction — 3 months (paragraph 2)

This covers cases where the return was right when filed but its premise later collapsed. Even after five years, a request can be made within three months of learning that the ground arose.

What they share is that the taxpayer is not at fault: circumstances unknowable at filing were settled later. So the five-year door reopens, but only briefly: three months from learning of it.

The authority must answer within 2 months (paragraph 3)

The head of the tax office receiving a request must, within two months of receipt, determine or correct, or give notice that “there is no reason to correct”.

What if there is no answer? Even before receiving notice, the requester can proceed to an objection, a request for review or other appeal from the day after those two months end. This prevents the authority from running down the clock through silence.

Returns after the deadline (Article 45-3)

A person who did not file by the statutory deadline can file a return after the deadline until the head of the competent tax office determines the tax and gives notice. Any tax due must be paid (paragraph 2).

The authority must determine or correct and give notice within three months of the filing date (paragraph 3). If there is an unavoidable reason, such as an investigation that takes a long time, it must notify that reason.

The non-filing penalty tax (Article 47-2) is also reduced, but by less.

For amended returns the reduction continues for up to two years; for returns after the deadline it ends at six months. The maximum reduction is 90% versus 50%. Filing and getting it wrong is not treated the same as not filing at all.

Getting back money paid in error (Articles 51–54)

Determining and offsetting national tax refunds

When there is an amount paid in error or overpaid, or a refund due under the tax laws, the head of the tax office must immediately determine it as a national tax refund (Article 51(1)). It does not wait for a claim.

But rather than paying it out at once, it first offsets it (paragraph 2) against:

1. national taxes payable under a payment notice;
2. national taxes in arrears and enforced collection costs (including arrears at other tax offices);
3. national taxes to be paid voluntarily under the tax laws.

When a refund is offset against arrears, the arrears are treated as extinguished retroactively to the later of the statutory payment deadline of the tax in arrears and the date the refund arose (paragraph 3). This retroactivity tidies up the calculation of additions and refund interest for the period in between.

National tax refund interest (Article 52)

When offsetting or paying, an amount calculated at the rate set by presidential decree is added for the period from the starting date to the offset date or the payment decision date. It is interest for the time the state held someone else’s money.

However, no refund interest is added when a refund is made through handling a grievance (paragraph 3). Refunds following a request for correction or a decision or judgment on appeal still carry interest. The law distinguishes what was won by asserting a right from relief granted at the administration’s discretion.

Prescription of the right to claim a refund — 5 years (Article 54)

Rights to national tax refunds and refund interest are extinguished if not exercised for five years from when they could be exercised.

The periods in one line

What remains

• The calculation of each penalty tax (Articles 47-2 to 47-5) should be studied together with the individual tax laws. This chapter dealt only with reductions (Article 48).
• Appeals against a rejected request for correction belong to chapter 7 (review and adjudication).
• The “grounds specified by presidential decree” in Article 45-2(2)5 are in Article 25-2 of the Enforcement Decree and change often.

The next chapter covers appeal procedures: how objections, requests for review and requests for adjudication differ, and why they must be exhausted before administrative litigation.

References

• Korea Law Information Center, Framework Act on National Taxes, Articles 45, 45-2, 45-3, 46, 48, 51, 52 and 54 (in force 11 August 2026, Act No. 21860; checked 2026-09-20)