You can issue a refund to your customer any time you like, up to one year from the date of the echeck. If you are asking how long a customer can request a chargeback; it depends on the situation. In most cases, a customer can request a chargeback from their bank up to 90-days from the date of the transaction, or 3 statement cycles. If the customer claims outright fraud, they may be eligible for a chargeback by law up to 365-days after the transaction processed.