Every time you complete a level you will earn extra gold (1.5x the gold received from level completion), which goes to the Piggy Bank. The extra gold you earn in the Piggy Bank is only available to claim once the amount you've collected reaches or exceeds 3,000 gold. When the gold reaches 9,000 you will not get extra gold again. The Piggy Bank resets every day at 00:00 server time.