The date of registration is important when it comes to depreciating the car in terms of age. For example:
A car registered in December 2004 will be 6 years and 3 months old in March 2011; hence it will fall into the tax bracket of 7-6 years old whose CRSP depreciation is 60%. Whereas a car registered in January 2004 will be 7 years and 2 months old in March 2011, hence falls into the 7-8 year old tax bracket whose depreciation is 70%.
In order for the CRSP value to be depreciated by a greater amount thus resulting in lower import taxes, it is ideal for you to import a car registered in the month preceding it arrival.
As for the calendar year issue, you will not be allowed to bring a 2003 registered car in 2011 even if the car isn’t 8 years old. For example a car registered in Dec 2003 will be 7 years and 4 months old in March 2011, will not be allowed into the country, although it falls within the KRA age bracket (of up to 8 years).
I’m not very sure about how the time when you actually pay the duty affects the process. However I think if your import declaration forms (IDF) have been accepted then it doesn’t really matter when you pay your duty, only thing is that port charges will be accumulating (but KRA/KPA will possess your car and auction it after a certain time frame). The most important thing is for your car to arrive before the deadline for the year/age comes into effect.
For Clearing I would recommend Agility Logistics, have worked with them for quite some time and have never been disappointed. Cargo is usually cleared within a week and without any stress.
You can check the registration date of the car you wish to import from Japan by entering the VIN/ chassis number on the following link:
http://www.sbtjapan.com/chassischeck.aspx
Before you can be be old and wise, you must first be young and stupid.