You have a couple of options for installment payments for your customers.

The newest way is perhaps the easiest way for you to manage, but I don't know a lot about it. Square now offers Installments via their Capital program. Check out their Installments FAQ page for more information. This is a really new program, so you'll have to get it turned on for your account. There are instructions on how to do that on the FAQ page.

Or you can set up Recurring Invoices for the payments. The steps below assume you're using Square's online store environment for the initial purchase. If you're using a third-party website, make sure you have a way to get the customer's email address from the order.

• Have the price of your item on the online store be the price of one of the installment payments at least.
• Once the customer has completed the purchase, send them a welcome email that explains the following: They ordered an item that is to be paid in installments. You are going to use their email to send them an invoice that has a spot for them to enter and save their credit card information. You will charge $xxx monthly for xx months.
• Go into your dashboard (or Point of Sale) and create a recurring invoice. Set the payment arrangement just as you said in the email and send to the customer.

As long as the customer holds up their end of the deal, your payments will automatically be sent to you on the schedule you choose.

Please note that the Recurring Invoice trick does leave you open to problems since you're relying on them to fulfill their end of the deal for that first payment, but if you know your customer it usually works out fine in the end.

More info about Recurring Invoices.

Hope this helps!