Fresh off of its massive partnership with Starbucks that turned the still-young company into the US' largest mobile payment network, Square has just opened up a new flat-rate processing fee for small businesses. The new option costs $275 per month, and that's all you'll have to pay so long as you don't accept more than $250,000 per year using the service. The other option for small business owners has long been Square's 2.75 percent fee per swipe, but if you collect more than $120,000 per year you'll now be better off using the flat-rate option. However, it's also worth keeping in mind that any charge over $400 will not be covered under the new plan — you'll have to pay the standard 2.75 percent fee on any of those purchases. The new flat-fee pricing structure — fairly new ground for credit card processing companies — is undoubtedly a move to keep customers from moving over to its recently-introduced competitor PayPal Here, which charges 2.7 percent on purchases.