Precoro makes the calculation of your budgets and allows to create Purchase orders and Invoices only for the available budget sum.

This is made to restrict exaggerated budget usage and track resources available for future purchases. 

The available budget sum is counted by the following form 

Available sum=Budget sum - the sum of the Purchase orders that do not have Invoices created - Sum of the Invoices created manually (without Purchase orders) - the sum of the Invoices created on PO - the sum of Purchase orders available for further Invoice creation.

For example: 

The budget amount is 5000 USD. They have Invoices for 500 USD created from Purchase orders, Invoices created manually sum is 250 USD and we have Invoices created from PO's for 1750 USD. Also, we have 1 Purchase order for total sum 1000USD and only one Invoice created for it for 550 USD, although the PO sum for this Invoice was 500 USD. 

My budget sum will be:

5000 - 500-250-1750-550-500= 1450 USD