Tempo Remaining Estimate Calculation based on Bill Estimate

[Anu]

Hi 

I have a issue traking my Remaining Estimate .I have a field called "Billed " which tracks only the billing hours. So I want to Track my Remaing estimate based on the Billing hours but not based on the original estimated hours .

Is there any possible way to do that for all the issues. when ever any user logs work?

Thanks