Yep! If you accept a payment while you are in Offline mode, the Square Register is simply recording that payment information but the transaction will not be processed until you reconnect to the internet.
There are a few more risks with taking payments in offline mode as payments are not processed until you reconnect, you will not know right away if a card is declined and you need to connect to the internet within 72 hours for the payments to process. If you have pending offline payments, do not delete the Square app. Pending offline payments will be permanently lost and the funds won’t be captured if the app is deleted. Make sure you process these payments by re-connecting your device to the Internet.
Check out our Support Center for all of the information you'll need to know before accepting payments in offline mode.
