Self-employed taxpayers who filed their global income tax return in May may be surprised to receive another tax notice in November — but the bill is not a duplicate. Here is what the interim prepayment system means, who it covers, and how to manage it if business has slowed.
[Editor's note] Taxes touch every citizen's life, yet the complexity of tax law and its unfamiliar terminology make the subject daunting for many. Understanding income tax, property tax, the comprehensive real estate tax, inheritance tax, gift tax and other levies that affect daily life is the foundation of sound financial management. The Herald Business is launching "Yun Yu-jin's Tax Talk," a series produced with Seoul Metropolitan Council member and accounting and taxation doctoral degree holder Yun Yu-jin. The series will cover everyday tax knowledge, major tax reform, tax-saving strategies and policy debates — explained clearly and accessibly for ordinary citizens. The goal is to serve as a practical tax guide that deepens taxpayers' understanding and strengthens their rights. Yun holds a master's degree in tax law from Yonsei University and a doctorate in accounting and taxation from Gachon University. Yun serves as a 12th-term Seoul Metropolitan Council member on the Education Committee, heads Yun Yu-jin Tax Accounting Office, works as an adjunct professor in the department of accounting and taxation at Gachon University, and previously served at the National Tax Service (March 2021–July 2017).
November global income tax interim prepayment: what to check when the notice arrives.
Self-employed workers who filed and paid their global income tax return last May may be caught off guard when another tax notice arrives just months later. The November bill, however, is not a case of double taxation on the same income — it is an "interim prepayment," a system that requires taxpayers to pay a portion of the following year's global income tax liability in advance.
The fifth installment of "Yun Yu-jin's Tax Talk," a series that unpacks everyday tax questions, explains the concept of the global income tax interim prepayment, who must pay it, how the amount is calculated, when it is due, and what options are available when business performance has been poor.
Global income tax is levied on an individual's combined income — including business income — earned over the course of a year, with the return filed and paid the following May. The interim prepayment system, by contrast, requires taxpayers to pay a portion of the tax on income earned in the first half of the current year, with that payment due in November.
The most important feature of the interim prepayment system is that it does not require every taxpayer to calculate and report first-half income from scratch. In most cases, the National Tax Service calculates the interim prepayment amount based on the taxpayer's global income tax payment record from the previous year and issues a notice accordingly.
For example, if the interim prepayment base amount for last year's global income tax was 8 million won ($5,890), the interim prepayment due this year would in principle be half that amount — 4 million won. The taxpayer pays the notified amount in November, then deducts that prepayment from the final tax liability when filing the definitive global income tax return the following May.
The interim prepayment is therefore best understood not as paying taxes twice, but as spreading the annual tax burden across two installments. The actual interim prepayment base amount may not be determined solely by the previous year's confirmed tax payment, however, so verifying the figure the National Tax Service calculates is important.
Not receiving a notice does not necessarily mean something has gone wrong. Taxpayers whose interim prepayment amount falls below 500,000 won are generally excluded from the notification requirement. Certain categories of taxpayers defined by law — including newly registered business operators — are also exempt from the interim prepayment obligation.
Salaried workers with only employment income, for instance, are not subject to the global income tax interim prepayment at all, so taxpayers need to understand their own income type and tax obligations clearly.
On the other hand, self-employed individuals who performed well last year but have seen sales fall sharply this year may find the interim prepayment amount — calculated on the basis of last year's tax record — difficult to bear.
In such cases, a mechanism called the "estimated interim prepayment filing" is available. If the estimated interim prepayment calculated on the basis of the current year's first-half business performance falls below 30 percent of the interim prepayment base amount, the taxpayer may, subject to certain conditions, file and pay based on that estimated figure instead.
In other words, if business was strong last year but income has dropped significantly this year due to an economic slowdown and falling sales, the taxpayer can adjust the tax burden by basing it on actual first-half results.
A taxpayer must not, however, simply reduce the notified amount on their own just because sales have declined. The relevant conditions must be met, and the estimated filing procedure must be completed within the prescribed deadline.
The payment deadline also requires close attention. The statutory due date for the global income tax interim prepayment is Nov. 30. Missing the deadline can trigger a late-payment surcharge, so taxpayers should check the amount and due date printed on the notice beforehand.
When the interim prepayment exceeds a certain threshold, an installment payment option is also available. If the interim prepayment exceeds 10 million won, a portion may be paid in installments within the limits set by law, helping to ease the short-term cash burden.
If a taxpayer faces circumstances recognized by law — such as a natural disaster or serious business hardship — an extension of the payment deadline may also be considered. The eligibility requirements and procedures for installment payment and deadline extension differ, so both should be confirmed in advance.
Above all, taxpayers should neither pay the notified amount without question nor assume they have no tax obligation simply because they did not receive a notice. Reviewing one's income type, previous year's tax payment record and current business situation together is the starting point for avoiding unnecessary tax burdens.
Through this installment of Tax Talk, Yun said taxpayers should understand precisely what the November global income tax interim prepayment system entails and carefully verify the filing and payment procedures that apply to them.
The November global income tax notice can serve as more than a simple payment reminder — it is an opportunity to review the year's income and tax obligations. Checking whether the notified amount is appropriate, whether one qualifies for an exemption, and whether an estimated filing based on declining business performance is possible are the first steps toward sound tax management.
7toy7@heraldcorp.com
