help! calculating discount/tax on subform!!

[rgt3]

i hope someone can help. i'm working on a sales order form. the subform lists each item purchased by the customer. i've successfully created an order subtotal which sums all the item totals. however, senior citizen customers recieve a 5% discount. the discount is listed under my customer table. how can i make a formula to calculate the subtotal * senior citizen discount?? this also relates to the tax calculation. how do i calculate subtotal * the tax rate?
sorry....i'm VERY new with access and having alot of trouble understanding the calculations. please answer asap!!

 

[CEH]

Looks like you have really answered your own question. You have said you are storing the customers discount in a table. So on your form you would have an unbound textbox,(maybe called..[CustomerDiscountAmount]) it's control source would be your calculation. =([subtotalTextboxName]*[CustomerDiscount]) or you might need =nz(([subtotalTextboxName]*[CustomerDiscount]),0)
This would give you your discount amount.
Then another unbound textbox to add the sub total and the discount amounts, for a grand total.
One thing to think about... usually the rule is calculated fields are not stored.... BUT.. there are exceptions. Tax rates change and maybe your discount rate.... So if they DO change you might want the results stored in a table. You can then change rates without altering the history.

 

[rgt3]

what is #Error??

I tried the expression =([Order Subtotal]*[Discount]) in the control source of the "Senior Citizen Discount" textbox properties. However, when I look at the form in database view, the textbox reads #Error instead of the discount amount. If my customer discount is stored in the customer table, how do I tell Access to multiply that discount times the customer's order subtotal? I'm so confused!!!