Problem with Budget PS and taxes purcharse order

Hi Experts,

Please I need a help

I have a budget of $ 1000 dollars

i created a order purchase for 100 dollars is a tax of 18 dollars,  Total 118 dollars

when I check the budget is committed only 100 dollars, Not 118 dollars.

This is correct according to standard SAP? or is there some configuration that allows compromising the 118 dollars?

regards,

Augusto