Key Date for Car Tax: April 1
Annual car tax payments are due in May. You will get a notice around the end of April from the Tsuchiura Tax Office that will detail the amount that you have to pay. The deadline for payment is May 31, 2007. The payment is based on the size of your engine and the prefecture that your car is registered in. If you want to get an idea of how much your bill is going to be, have a look at the 2006 figures on the Ibaraki Prefecture website (in Japanese).
I would estimate that most cars that are owned by new foreign residents of Tsukuba should fall within the 30,000 yen to 40,000 yen range (between 1000cc and 2000cc). (The rates may be different this year, and these rates are only applicable to cars registered in Ibaraki.)
Please note that keijidosha or “light vehicles” are taxed differently. Regular-sized vehicles are taxed by the prefecture, but light vehicles and motorcycles are taxed by the city. The tax rates for light vehicles are much lower (the most expensive category is currently 7200 yen). This is one very good reason to buy a yellow-plate car.
If you are going to be in Tsukuba for more than one year, you may want to set it up so that your car tax payments come directly out of your bank account.
The reason why I am mentioning this today rather than some time in April is that the tax is charged to the person who owned the vehicle on April 1 of any year. The person who owns the car on April 1 is defined as the person whose name is on the ownership certificate (not necessarily the person who actually possesses the car on that day). So, if you are leaving Japan and you want to sell your car, make sure the name change has been completed by April 1 so the new owner will have to pay the tax. If you are buying a car, it might be a good idea to wait until after April 1 as the current owner will then have to pay the tax.
I should also mention that if you sell the car after April 1, you will not get a pro-rated (meaning proportional) refund for the tax that you pay UNLESS you sell the car to someone in another prefecture AND that person registers the car in that new prefecture. So, if you sell the car to someone in Tsukuba (or anywhere else in Ibaraki), you may want to try to include the amount that you spent on car tax in the selling price of the car.