We take your voucher offline when the budget is 80% used so that it is no longer visible to new customers. We allocate the remaining 20% to cover for redemptions of customers who have already collected the voucher. For customers who have already collected the voucher before 80% of the budget was reached, we allow them to redeem vouchers for a window of approximately 30 minutes after we disable the voucher discovery. In cases where 20% of your budget does not cover for the customer redemptions until the expiry date, you might see your spend exceeding your budget. The risk of spend exceeding the budget decreases for higher budget amounts.
For budgets under £ 10.000, you might expect a spend overshooting up to 15% (or more) of your budget.