When you use Stripe as your payment gateway, any transaction fees are deducted automatically. If you later decide to refund an order, the transaction fees aren’t returned. So, if you were to refund all payments in one go (e.g. if you cancel an event), there’s a chance your Stripe account would go into a negative balance.
We checked with Stripe to see how they handle this, and they say:
When you carry out a refund to a customer, we first look at your available Stripe balance to cover the amount. If you do not have a sufficient available balance and carry out a refund, your Stripe account will then become negative. Negative balance handling varies from country to country.
If your Stripe account is registered in Australia, Canada, USA or the UK, we will attempt a withdrawal from your bank to bring the account to a positive balance again. If we are unable to debit your bank account, we may require you to send a wire transfer to cover the negative amount.
If your Stripe account is registered in Continental Europe, Hong Kong, Singapore, Japan, Mexico or Brazil. we wouldn’t attempt a withdrawal from your bank account. You may be required to send a wire transfer to pay off the negative balance.