In Korea, once your annual financial income (interest plus dividends) passes 20 million won, only the portion above that line is folded in with your other income and taxed at comprehensive rates. Health insurance runs on a different clock — the moment interest and dividends together clear 10 million won, it is not the excess but the entire financial income that gets counted as non-wage income.
Because the two thresholds are offset, there is a band where your tax bill does not move at all while a new health premium appears. For a salaried worker who already books 15 million won of rental income, moving financial income from 10 million to 11 million won — a single million won — keeps them out of comprehensive taxation but adds about 480,000 won a year in premiums.
Three lines matter here: 20 million won for comprehensive taxation, 10 million won for when health insurance starts aggregating, and 20 million won again for when the non-wage premium is actually levied. Confuse what each number counts and the arithmetic falls apart.
The tax line: up to 20 million won, 15.4% is the end of it
The National Tax Service counseling center explains that comprehensive taxation applies only when financial income exceeds the 20-million-won threshold. Up to that amount, it is taxed separately at 14% income tax plus 1.4% local income tax, and only the excess is combined with other comprehensive income. The threshold is judged per individual — spouses are not added together.
The most common misreading is that crossing 20 million won pulls the whole amount into comprehensive taxation. Only the excess is aggregated. And since 15.4% has already been withheld even on that excess, what you actually pay extra is the gap between the post-aggregation rate and 15.4%. If your other income is small enough to keep the tax base in a low bracket, the additional burden can be effectively zero. The mechanics of how 15.4% is assembled at the withholding stage are laid out in the piece on dividend income tax calculation.
The premium line opens at 10 million won
Korea's official Easy Law portal sets out the non-wage income premium for employee subscribers as follows. It is charged only when annual non-wage income exceeds 20 million won; the monthly income base is (annual non-wage income − 20 million won) × 1/12; and the rate is 719 per 10,000. The monthly cap on the non-wage premium is 4,591,740 won. Then comes the decisive clause — if interest and dividend income together are 10 million won or less, that interest and dividend income is not aggregated at all.
Read in reverse: cross 10 million won and the full amount of financial income enters non-wage income. Ten million won is not a billing threshold but an aggregation switch. Once the switch is on, what decides whether you are billed is the 20-million-won total of non-wage income.
The applicable rates changed for 2026. The Ministry of Health and Welfare announced that the 2026 health insurance rate is 7.19%, 0.1 percentage point above 2025. In a separate release, the 2026 long-term care insurance rate was set at 0.9448% of income. Added together, the rate actually applied to the monthly income base is 8.1348%.
| Threshold | Amount | What it counts | Once crossed |
|---|---|---|---|
| Comprehensive taxation of financial income | 20M won | Interest + dividends, per person | Excess folded into comprehensive income |
| Health insurance aggregation switch | 10M won | Interest + dividends combined | Full financial income added to non-wage income |
| Non-wage premium levied | 20M won | Total non-wage income | Excess ÷ 12 × 8.1348% |
| Dependent income requirement | 20M won | Aggregate income (financial income included) | Dependent status lost |
How much does one extra million won in financial income cost in premiums?
Holding rental income fixed at 15 million won for an employee subscriber, only financial income was varied. The 8.1348% figure — 7.19% health plus 0.9448% long-term care — is applied to the monthly income base.
| Financial income (10k won) | Aggregated? | Total non-wage income (10k won) | Monthly base (won) | Monthly premium (won) | Annual cost (won) |
|---|---|---|---|---|---|
| 900 | Excluded | 1,500 | 0 | 0 | 0 |
| 1,000 | Excluded | 1,500 | 0 | 0 | 0 |
| 1,100 | Fully aggregated | 2,600 | 500,000 | 40,674 | 488,088 |
| 2,000 | Fully aggregated | 3,500 | 1,250,000 | 101,685 | 1,220,220 |
| 3,000 | Fully aggregated | 4,500 | 2,083,333 | 169,475 | 2,033,700 |
Between 10 million and 11 million won of financial income, 480,000 won a year appears out of nowhere. On the tax side both cases end at 15.4% separate taxation, so the difference is zero. The tax on that extra million won is 154,000 won — the premium it triggers is more than three times as much. Going from 20 million to 30 million won, by contrast, starts comprehensive taxation but raises premiums proportionally (about 810,000 won a year). The step sits near the 10-million-won mark.
One premise carries this calculation: 15 million won of rental income already exists. With no other non-wage income and financial income of 11 million won, the non-wage total never clears 20 million won and the premium is zero. What builds the step is not financial income alone but the total after the switch is flipped. The 10-million-won line only bites for people who already have rental or business income.
Tax follows only the part above 20 million won; health premiums, once you pass 10 million, look back at the very first won.
If you are a dependent, there is one more line
The non-wage premium is a story about employee subscribers. For someone registered as a dependent on a spouse's or child's coverage, paying nothing themselves, a different line is drawn. Mirae Asset's Investment and Pension Center summarizes the income requirement for dependent status as business, interest, dividend, pension, wage and other income combined staying at or below 20 million won a year. Only public pensions such as the National Pension count; retirement and private pension income is excluded from the test. The asset requirement is a property tax base of 540 million won or less across land, buildings, housing, vessels and aircraft.
There is no 10-million-won switch here. Financial income enters the aggregate in full whatever its size, and once the total clears 20 million won the status disappears. Losing it means converting to a regional subscriber, with premiums recalculated on income and property — not the employee structure where only the excess above 20 million won is charged. For a retiree with no earned income who is raising their dividend allocation, this line binds before the tax one does.
What to watch
- The 10-million-won financial income line — if you have other non-wage income from rent or business, calculate whether crossing this line pushes the total past 20 million won.
- The non-wage income total — billing is decided on the total, not on financial income alone. In a year when rental or business income rises, revisit the financial income threshold too.
- The 2026 rate of 8.1348% — 7.19% health plus 0.9448% long-term care. It is reset by ministry announcement each year, so check the number for your own calculation date.
- The 20-million-won dependent test — full aggregation with no switch, and crossing it removes the status itself. If you are registered as a family member's dependent, this line comes first.
- Which year's data was used — check on your premium assessment record which year's non-wage income figures were applied. The year income rises and the year it is billed can differ.
References
- National Tax Service counseling center — taxable financial income
- Easy Law — health insurance premium calculation for employee subscribers
- Ministry of Health and Welfare — 2026 health insurance rate set at 7.19%
- Ministry of Health and Welfare — 2026 long-term care insurance rate of 0.9448%
- Mirae Asset Investment and Pension Center — health insurance dependent requirements