Homeowners in Taiwan's Yunlin County who live in their own homes could pay up to four times more tax next year if they miss a paperwork deadline — bad news for anyone who forgets, easily avoided for everyone else.

• Owner-occupied homes valued under about NT$1.85 million qualify for the lowest 1% house tax rate next year.
• The catch: the owner must register their household residency at that address before March 22 next year.
• Miss the deadline and the home gets taxed at the non-owner-occupied rate, which tops out at 4.8% — roughly four times the 1.2% owner rate.
• To qualify, the home cannot be rented out or used for business, the owner or close family must actually live there, and the family must own just this one home nationwide.
• Yunlin has about 204,000 taxed homes; roughly 68,000 meet the conditions for the cheapest rate.

Outlook: Expect a rush of household registration filings ahead of the March deadline, with tax authorities pushing reminders through the winter.