Steps:

Apportion whole budget amount across all periods

1. Select an account from the account list in the General tab and switch to the Budget tab.
2. Select the Fiscal Year to which the budget will apply. You can create budget details for the current and future fiscal year.
3. Enter the total budget amount in the Total Budget To Allocate field and click on the Apply button. The total amount is divided equally across periods.
4. Save the details before closing the form.