Tax to calculate amount based on period of contract and rates applicatable for that periods

Hi All

In case of service part sales, currently tax is calculated based on the current applicable rate i.e 5%.

But in case this contractual period extends beyond April-14 then for the period April-14 till Sep-15 tax should get calculated @ 8% and if the contractual period extend beyond Oct-15 the tax should be calculated @ 10%.

Since currently tax calculation is based on currently pevailing rate, business has to manually take care of additional tax amount.

Is there any tax functionality which we can use to get correct tax populated on AR invoice

Regards,

Rahul