Do you wants to integrate odoo budget with purchase order and Vendor Invoice Bills then don't worry using this odoo apps user can integrate accounting budget management with purchase order and vendor bill based on analytic account.
After installing this apps you can have option to allow and restrict validation of purchase order against budget amount. If you restrict override budget amount then once the purchase order or vendor bills amount is threshold limit against budget planned amount then user not allow to confirm or validate those purchase/vendor bills. But if you allow the override limit on purchase order then user can able to confirm or validate purchase order or vendor bill after the threshold or exhausted budget planned amount and you will see the actual amount on more than planned budget. This apps is very useful to plan your periodically accounting budget of your company.

Budgets Menu

Users can create a budget under Invoicing > Accounting > Budgets menu, User can allow or restrict override budget amount.

Purchase Order

Users have to select "Analytic Account" on the purchase order to apply the budget on a purchase order.

Vendor Bill

Users need to validate the vendor bill of a purchase order to apply the budget to the purchase order.

The purchase order or vendor bill amount will be decreased from the budget based on the analytic account selected on the purchase order.

Restrict Override Budget Amount

If the override amount is "Restrict" and the user tries to confirm a purchase order or vendor bill with a large amount compared to the budget amount then it will raise a warning.

Allow Override Budget Amount

If the user set an "Allow" override budget amount then purchase order or vendor bill with the large amount then the budget amount can be confirmed or validated.

Override Budget

Users can see the override budget with a greter "Practical Amount" than "Planned Amount".