Tax Types effective date & ending date

I would like to suggest effective date & ending date for each tax type. This is very useful when tax rate changes are announced by Government. For example, standard VAT rate is to change from current 20% to 17.50% from 4/12/2012. You can add a date line for this tax rate today with effective date as "04/12/2012" and ending date as blank. on the previous date line, ending date is set to 03/12/2012. This is also important for deliveries done on or before 03/12/2012 but not invoiced (for both sales & purchases). A user producing invoicing against delivery or supplier invoices for purchase orders, say on 7th, will get wrong tax if we change the tax rate on 4th morning to new tax rate. If we have date line for each tax type, any sales delivery received or PO delivery will look to tax type date range and according apply the correct rate tax for the date of purchase invoice/sales invoice.

Deven