Car Tax Prepayment: Timing Changes the Discount

For non-commercial passenger cars, car tax is normally billed in two installments, June and December. Prepayment lets you declare and pay the remaining amount for the year in one go instead, in exchange for a partial discount. Four windows open each year — January, March, June and September — and which one you use changes how much of the year the discount covers, and therefore how much you actually save. As of 2026 the discount rate sits around 5%/yr (a scheduled step-down has been deferred), a figure your local government republishes annually, so check the latest notice on Wetax before applying.

The discount isn’t a flat cut on the full year — it’s prorated to the months remaining after the application month. Applying in January covers the longest remaining stretch, so it earns the largest discount; by September, the remaining stretch is short and the discount shrinks accordingly. In the example above (a new 2,000cc car), January yields about 23,800 KRW versus roughly 6,500 KRW in September — a meaningful gap from timing alone. The takeaway: all else equal, January is the best window, and if you miss it, catching March as early as possible is the next best move.

Applications go through Wetax (wetax.go.kr), on the web or the app, from anywhere in the country. The typical flow is ① log in with a digital certificate or simple authentication → ② open the local-tax filing menu and pick car tax prepayment → ③ pull up the vehicles registered under your name and select the one to prepay → ④ review the calculated amount and pay immediately by transfer or card. The online filing window generally runs Jan 16–31, Mar 16–31, Jun 16–30 and Sep 16–30 — that is, from mid-month to month-end. Dates can vary slightly by municipality, so check Wetax notices for the exact schedule. Traffic tends to spike right before the deadline, so it’s worth applying with some room to spare.

For an older vehicle, the age discount (kicking in from year 3, growing yearly up to a cap) applies first to lower the displacement-based tax, and the prepayment discount is then calculated on that already-reduced figure. A new car and an aging car of the same displacement therefore end up with different annual tax amounts — and different absolute prepayment discounts — but the underlying rule that "earlier is better" applies identically to both. To see the exact figures for your own vehicle, entering its displacement and age directly gives the clearest answer.

Missing all four windows carries no penalty. Without an application, the tax simply reverts to the default June/December installments — you just don’t get the discount, with no late fee or surcharge attached. If you’ve just registered a new car or had ownership transferred to you, you can still apply from the next available window, so check Wetax for eligibility right after registration. If you tend to forget the dates, signing up for Wetax or local-government reminder alerts (text or app push) is a simple fix.

To see the exact annual tax and prepayment discount for your own car, try the car tax calculator with its displacement and age. To review your broader annual tax picture alongside car tax, the comprehensive income tax calculator is a useful companion. This guide was written as of 2026-07-19; the discount rate and application windows are republished annually by local governments, so confirm current notices on Wetax before applying.