Resale and Capital Gains: What Tower Mansion Sellers Owe in Tax

When you resell a tower mansion in Japan, the tax rate on the gain depends heavily on how long you owned the unit — and the gap between short-term and long-term rates is large enough to change the economics of selling a year early or late.

1. The five-year line is the key threshold

Japan taxes real-estate capital gains at roughly 39% (short-term) if the property was held five years or less as of January 1 of the sale year, versus roughly 20% (long-term) if held longer. That's not a rounding difference — it can be worth years of appreciation on a single sale.

2. The holding-period clock starts on acquisition, not contract signing

The relevant date is typically the registration and acquisition date, and the comparison point is January 1 of the year of sale — not the sale date itself. A sale in early January can fall on the wrong side of the line even if the actual five-year anniversary is only weeks away.

3. Deductible costs reduce the taxable gain, not just the price

Acquisition costs, certain improvement costs, and selling expenses such as agent commission can offset the taxable gain. Sellers who only calculate purchase price versus sale price often overstate their tax exposure.

4. Primary-residence exemptions may apply, but have conditions

An owner-occupied primary residence may qualify for a special deduction, but investment units and units that haven't been the seller's primary residence for the required period typically don't qualify. This is worth confirming with a tax professional rather than assuming.

Checklist

• Exact holding period as of January 1 of the intended sale year
• Whether selling slightly later crosses the five-year threshold
• Documented acquisition and improvement costs to offset the gain
• Whether the unit qualifies for a primary-residence exemption

Timing a sale around the five-year line is one of the few tax decisions a seller has real control over — worth modeling before, not after, listing the unit.