Hello Mate!!

Adwords allow to provide me 20% over-delivery basis on my daily budaget.
Suppose my daily budget is $10.
If Google provide me over-delivery for 3 days in a month then how they calculate?
My calculattion is:
My Daily Budget is : $10
20% Over-delivery (basis on daily budget for 3 days) : $6

Google Said that you can no pay more than $304 in a month (Daily budget $10 x 30.4 average months days)

But here my billing reached $306 (Including 3 days over-delivery)
So I pay only $304 than what about $2 ?
They can count this $2 on my next billing?

In simple words, they are credited this $2 on next month billing?
Reply me soon.