Vehicle Tax Proration Calculator (Japan)
Estimate the prorated Japanese automobile tax when you register a regular or compact car partway through the fiscal year, or deregister (scrap) one. Enter the displacement, fuel type, and registration date to see the estimated amount due or refunded.
Tips
- The first registration date appears on your vehicle inspection certificate (shaken-sho). When scrapping a used car, enter the date it was first registered by its original owner.
- New registrations are taxed from the month after registration, while deregistrations are taxed from April through the month of deregistration — the counting rule shifts by one month between the two.
- Kei car tax has no proration system and is charged in full to whoever owns the car as of April 1, so this tool only covers regular and compact cars.
- Registering a car in March means the next fiscal year already starts in April, so the taxed months for that fiscal year come out to zero.
Frequently asked questions
Side Note — Why registration and deregistration count months differently
Japan's vehicle tax proration system exists to reconcile the annual tax, which is fixed as of April 1, with how long a car was actually owned. Without proration, someone buying a new car partway through the year would owe a full year's tax despite driving it for only part of that time, while someone scrapping a car early in the year would keep paying tax for months they no longer owned it. Prorating the amount by month is a practical way to reduce that mismatch.
It is easy to overlook that new registrations and deregistrations count the registration/deregistration month itself differently. A new registration is not taxed for its own month — counting starts the following month. A deregistration, on the other hand, includes its own month as part of the taxed period for that fiscal year, with the refund beginning only the month after. The same calendar month is counted from opposite ends depending on whether you are acquiring or giving up the car.
Used car dealers sometimes work this calculation backward, advising buyers that registering early in the month is slightly better since the following month is where taxation actually begins. In practice the difference usually amounts to only a few thousand yen, but if you are buying or selling near the end of the fiscal year, shifting the registration date by even a day can change the number of taxed months — worth a quick check with the dealer.