Afterpay
When you miss a payment, Afterpay will immediately stop you from making any other purchases using Afterpay. You may get a 10 day grace period (unless you have another arrangement noted on your payment schedule). After your grace period is over, a late fee is charged to your Afterpay account.
Afterpay will only ever charge one late fee per installment and the total amount of late fees charged on an order will never exceed 25% of your initial order value.
If you have any further questions about Afterpay's late fees, we'd suggest reaching out to their support team.
Sezzle
When you miss a payment, it is automatically rescheduled in Sezzle's system and a fee is added to the instalment. From there you have 48 hours to complete the payment. As long as you log back into your Sezzle account and pay off the failed payment within that window, the fee is automatically waived.
If you have any further questions about Sezzle's late fees, we'd suggest reaching out to their support team directly.