Flat-rate credit card processing is good for businesses that want predictable credit card processing costs. Regardless of the transaction environment or card type used, you’ll know exactly how much it costs to process the payment. Flat-rate processing is also a good option for startups that want to process payments immediately without going through a lengthy underwriting process. If it sounds like flat-rate processing is right for you, sign up for Square. The fees are transparent, and they won’t lock you into a long-term contract. There are no setup fees or chargeback fees, and Square supports both in-person and online sellers.