Blunderbus
For your edification....
PAYE or PAYG is pay as you go or pay as you earn tax on a weekly/fortnightly/monthly basis. In hong kong we do neither PAYG/PAYE. Instead we pay tax in arrears. The tax bill you get for payment in Jan 2008 is for finalising 1 Apr 06- 31 Mar 07 tax and then guesstimating (they call it provisional) tax for 1 Apr 07-31 Mar 08. They only ask you for 9 months (that would be 75%) of the tax for the 07-08 tax year... you have actually earned the money before you pay it. The remaining 25% is paid in April AFTER you have earned the money that caused the tax. They (IRD) will then ask you to add to (90% of the time due to higher earnings than planned due increments and upgrades) the 'provisional' tax paid a year LATER in the following Jan. How is that taxing at 25%?
So in a typical career here, you will go about 12-36months without a tax bill, you then get one covering money earned or money to be earned UP TO the date you have to pay tax. They use the word Provisional as according to their 'payment up to a year in arrears' system it is in fact 'provisional' - to us it is just like tax in western countries (jump in any time 404;-) - ie what we call PAYG or PAYE.
If you never got promoted or had increments your tax would be spot on after the first return. So if you have been 'in rank' for a while and not suddenly bought or sold a house using CX scheme, or changed bases, when you leave the tax to pay will be approx 16% and will be close to the 'provisional amount'. If you leave before the Jan payment is due, they will have to prorata what was due to be paid. There is no surprise here. You will average up to 16% flat tax.
So to keep it easy, every Jan(75% - 9 months+previous years balance)/Apr(25% - 3months) you PAYG/PAYE. The only reason there is more tax in the next year than the previously provisionally paid amount is that people get promoted, increased increments etc.
There is no double tax early on or tax free years at end. For new joiners, just put away or 'allocate' 16% of your money and you will likely more than cover any tax bill as long as you do it from day 1.