A budget is arbitrary. We aren't talking about less goods sold in this situation, but adjusting expenses. If we can raise expenses we lower profits. Lower profits are lower taxes.

The previous years earnings are not double taxed, they are capital to use on expenses for the next year. The IRS only cares about the changes in assets from beginning of year to end of year

Edit: additionally, a project started but not completed, such as building and selling a house, or individual good sales, can be delayed until the next financial year if it is not sold or the project is completed.