Korea's 15M-Won Private Pension Line: 16.5% vs Full Tax

Once withdrawals from private pension accounts exceed 15 million won in a year, it is not just the excess but the entire amount that moves into either comprehensive taxation or a 16.5% flat separate tax. Up to 15 million won, tax is withheld at 3.3% to 5.5% depending on age and the matter ends there — so between 15,000,000 won and 15,010,000 won the bill jumps from 825,000 won to 2,476,650 won, a gap of about 1.65 million won.

That tripling, though, is the number you get if you choose the 16.5% flat tax. A retiree with almost no other income does better under comprehensive taxation, ending up with an effective rate below even 5.5%. The 15 million won line is not a cliff in the rate; it is the line where you have to pick your own calculation method.

Having a choice also means you can choose wrong. Where the dividing line sits moves with the size of the withdrawal, and it can be pinned down with a single formula.

Fifteen million won is not the line where the rate rises — it is the line where you must choose how your tax is calculated.

What counts toward the 15 million won, and what does not

What hits the threshold is the portion of private pension income arising from contributions that received a tax credit and the investment returns on them. Korea's National Tax Service states that separate taxation may be elected when this category of pension income totals 15 million won or less in a year. Read the other way: crossing that line changes the nature of the choice.

Two kinds of money fall outside it.

• Pension paid out of retirement-benefit money — Pension income whose source is severance pay is unconditionally separately taxed and does not enter the 15 million won calculation. If an IRP (individual retirement pension account) mixes severance money with personal contributions, only the personal side and its returns count toward the cap.
• Contributions that never claimed a tax credit — Money paid in without claiming the year-end credit is not taxable at all when it comes back out as pension. It affects neither the cap nor the tax.

The national pension runs on an entirely separate track, withheld through a simplified tax table and then settled or aggregated the following year. There is no need to add national pension receipts into the 15 million won arithmetic. The timing trade-off on that side is a different question, covered in the break-even math on early national pension claims.

Below the line, age sets the rate

Inside the cap the math is simple. The published withholding rates on private pension income are 5% under age 70, 4% from 70 to 79, and 3% from 80 up. A 10% local income surtax brings the actual deductions to 5.5%, 4.4% and 3.3%. Lifetime contracts that pay until death and cannot be cancelled early take 4% (4.4%) regardless of age, and where two conditions overlap the lower rate applies.

On the same 12 million won, a 69-year-old pays 660,000 won and an 81-year-old pays 396,000 won — a spread of more than 260,000 won. That is why pushing the start of withdrawals back a year or two is itself a tax decision.

The table below applies the published rates directly to several withdrawal levels. The three middle columns sit inside the cap; the last column applies 16.5% for amounts above it.

The trouble sits between the third and fourth rows. Ten thousand won more in income raises the bill from 825,000 won to 2,476,650 won — 1,651,650 won of extra tax. That single pair of rows explains why planners keep suggesting you cap withdrawals at exactly 15 million won and push the remainder into the following year.

Above the line: which is cheaper?

Past the cap, the choice is between the 16.5% flat tax and comprehensive taxation. Under comprehensive taxation the tax applies not to the gross figure but to what remains after the pension income deduction. That deduction is the full amount up to 3.5 million won; 3.5 million plus 40% of the excess up to 7 million; 4.9 million plus 20% of the excess up to 14 million; and 6.3 million plus 10% of the excess above that, capped at 9 million won.

Because the marginal deduction rate falls at each step, the deduction shrinks as a share of income as withdrawals grow. At a gross figure of 41 million won the deduction hits its 9 million won ceiling and stops rising.

The table below applies the deduction formula directly to show how much the taxable base actually shrinks.

Take someone drawing 15.01 million won with no other income at all. Taxable pension income of 8.609 million won less the 1.5 million won personal basic deduction leaves a tax base of 7.109 million won, which falls in the 6% bracket — a computed tax of 426,540 won, still under 470,000 won once the local surtax is added. That is less than the 825,000 won they would have paid at 5.5% by staying inside the cap. Crossing the line is not automatically a loss.

The break-even marginal rate

Which side wins depends on how much other income you have — that is, on your marginal rate. The two methods meet here:

Break-even marginal rate = 16.5% × gross pension ÷ taxable pension income

The formula exists because the flat tax hits the gross figure while comprehensive taxation only reaches what survives the deduction. Plugging in the table above gives 27.8% at 16 million won, 26.3% at 18 million, 23.7% at 24 million and 22.4% at 30 million. The larger the withdrawal, the lower the break-even rate — and the narrower the range in which comprehensive taxation wins.

The formula matches worked comparisons. A calculation by Josegeumyung Shinmun on a 16 million won pension shows that at a 26.4% rate comprehensive taxation costs 2.51 million won against 2.64 million for the flat tax, while at 38.5% the order reverses at 3.66 million against 2.64 million. The break-even of 27.8% falls neatly between the two.

A 26.4% combined rate corresponds roughly to a comprehensive tax base around 50 million won. Anyone with rental or business income pushing the base above that has reason to run the flat-tax numbers; anyone whose pension is essentially all of their income will usually find comprehensive taxation cheaper. The credit-stage arithmetic is covered separately in the conditions behind the 1.48 million won pension credit, and early-withdrawal rates in the split between 16.5% and 5.5% on early withdrawals.

Three caveats remain. Tax under comprehensive taxation is determined inside a progressive structure alongside other income, so the figures above are marginal-rate approximations. Electing comprehensive taxation surfaces the income and can raise national health insurance premiums. And where the two methods land within a hundred thousand won of each other, the choice barely matters.

What to watch

• How much of your pension actually counts — the number to test against 15 million won is total receipts minus severance-sourced payments and contributions that never took a credit.
• The age you start drawing — withholding drops from 5.5% to 4.4% at 70 and to 3.3% at 80. If you plan to stay inside the cap, the start date is the rate.
• The tax base of your other income — the 26.4% band, roughly a 50 million won base, is where the two methods trade places.
• Deduction as a share of gross — 42.6% at 15.01 million won, only 26.3% at 30 million. The bigger the withdrawal, the faster comprehensive taxation loses its edge.
• Health insurance assessment — for locally assessed subscribers, the premium effect has to be compared alongside the tax.

References

• National Tax Service — Withholding on pension income
• Josegeumyung Shinmun — Comprehensive vs separate taxation above 15 million won