Google AdWords can spend twice of your daily budget but you won’t be charged more than your monthly charging limit (Month will consider 30.4 day)
Let’s say you set your budget at 500 INR a day and your billing cycle is 30 days. Over the course of the month, you notice that your charges vary. Some days you’re charged 200 INR, on others you’re charged 1000 INR. But at the end of the month, your charges won’t exceed 15200 INR (that’s 30.4 multiplied by your 500 INR budget). So even though your campaign costs tipped above and fell below your 500 INR budget from day to day, at the end of the month, you’re still charged no more than what you budgeted.
Starting October 4, 2017, campaigns will be able to spend up to twice the average daily budget to help you reach your advertising goals, like clicks and conversions.
On days with lots of high quality traffic, your costs could be up to 2 times your daily budget. This spending is balanced by days when your spend is below your daily budget.
Keep in mind, you won’t be charged more than your monthly charging limit: the average number of days in a month (30.4) multiplied by your average daily budget.
According to AdWords Help