Field take value from another field

[AdrianS]

Hi ! I'm new here
Sorry if is repost,but I tried to find my problem and I didn't find anything!
My company hires contractors from a company. We estimate how much money we will spend for a contractor working on each project so we generate a "Work Order" for each project/contractor. I would like to make it so that the user can create new records for each "work order". Every time a "work order" is created, the dollar amount will be subtracted from the pre-approved budget.
How can I do that?
Thank you very much !

 

[Galaxiom]

Every time a "work order" is created, the dollar amount will be subtracted from the pre-approved budget.

Heading down the wrong track there. Don't decrement the budget.

It should be calculated from the opening budget less the total of work order values whenever the balance is required.

This also allows you to know the outstanding budget at any time in the present or past, and the future if you can enter projected work orders too.