Spreadsheet formula required

I am creating a spreadsheet which will calucate IHT exit charges and 10 year charges.

I have done everything except being able to get nil rate band put in automatically.

I would obviously create a list of nil rate bands which would be applicable for certain periods.  But then I would like to be able to enter a date and excel would pick the nil rate band appropriate to the date entered.

Is this possible in excel or would I have to enter the nil rate band manually?