31 January 2009
The c form is issued to get the benefit of concession tax on sales.
If you revise the price upward then for the difference either you have to collect tax or collect new c form for the difference amount.
If revision is downwards one method is you have to cancell the old c form surrender the original to the giver and collect a new c form. Another method is issue a credit note for sales and also for the tax amount.