Auto Query For A Form

Here I am again, I have a form for tracking payslips, on this form I have a field called "TAX YEAR" , "TAX PAID" and a field called "TAX YEAR TO DATE", when I run the form in ADD MODE I will be filling the field TAX YEAR (wich is 2006) and the field TAX PAID; what I need is that on the field TAX YEAR TO DATE i will have the total of all the TAX PAID for the year (in this case 2006).
I have a query wich exctract me this data, but I need it as a result on the form when the final user enetere the data!!!:eek: