You can either use the dynamic form feature and create the form fields on the fly and thus assign default values as you need them.

Or you can specify new 'system variables' (see other threads) and provide the logic to resolve those in the cformscheck_default_vars()routine.

…and you're using {finaltoal} as the default value for a given input field?

is you code that computes $finaltoalin the same function, or outside (make sure it actually has a value)

right, but cforms "runs in its own function" and thus won't have access to the outside defined, local $finaltoal variable. You might want to pass it on to $_GLOBALS['finaltoal']=$finaltoal;

Try:

to make sure you get that part working