MoneyLog｜부동산·경제 인사이트

| Thought it was tax-free… why does it turn into a 1 billion KRW tax?

These days, I hear this question very often during consultations:
“I own only one house… shouldn’t this be tax-free?”

But once we actually review the tax conditions, things often change completely.
One officetel, one hidden pre-sale right under a spouse’s name, or even a rooftop unit…
These seemingly minor factors can break the tax exemption and trigger heavy taxation.

And the problem doesn’t stop there.
This is not just a small increase in tax.
It can jump from tens of thousands to hundreds of millions — even close to 1 billion KRW.

Especially after May 9, 2026, when the temporary tax relief for multi-home owners ends,
one decision today can significantly impact your lifetime assets.

So today,
I will walk you through 9 real-world cases where tax exemption turns into heavy taxation,
explained step by step based on practical experience.

By the end of this article,
you’ll have a clear checklist to determine whether you are truly safe or not.

| Tax gap: how big is the difference?

It may not feel real until you see the numbers.

Let’s assume a capital gain of 1 billion KRW.

• Tax-free case: about 14 million KRW
• Heavy taxation case: about 640 million KRW

That’s more than 45 times difference.

And if penalties are added,

👉 Total tax can reach up to 900 million ~ 1 billion KRW.

The reason is simple:

You think you own one house, but the tax law does not.

Tax authorities consider:

• Actual usage of officetel
• Spouse’s hidden assets
• Inherited properties
• Rental housing status

All of these determine your “number of houses.”

That’s why tax-free status can suddenly turn into heavy taxation.

| 9 critical checks to avoid heavy taxation

• Officetel used as residence counts as a house
• Family cohabitation must meet strict conditions
• Temporary 2-home rule must be within 3 years
• Inherited property must be sold in correct order
• Rural house conditions must be satisfied
• Rental housing is not fully excluded
• Rooftop units can split one house into many
• Spouse’s assets are included
• Fake divorce leads to severe penalties

| What should you do before May 2026?

• Review tax conditions BEFORE signing a contract
• Recheck tax-free eligibility carefully
• Sell strategically before heavy taxation applies

If you assume you are safe without checking,
you may face a massive tax burden.

| Final takeaway

The biggest tax is the one you didn’t know about.

One wrong decision can cost hundreds of millions.

Share this information with someone you care about.