What the $40 covers

Taxes and fees being included is the figure to hold onto when comparing. A $40 advertised price elsewhere on AT&T's network is typically $44 to $48 once surcharges land, so the all-in framing is worth a few dollars a month on its own. 5G priority data is also named explicitly, which matters more than the headline price on a network where most budget plans are deprioritized during congestion.

You need an eSIM phone, and there is no way around it

Cash App Mobile requires an eSIM-compatible, carrier-unlocked device, an active Cash App account, and a Wi-Fi connection to complete setup. Compatibility is checked during sign-up. If the device does not support eSIM, the service cannot be used on it — there is no physical SIM to fall back on and no option to buy a phone from Cash App. Anyone on an older or carrier-locked handset is out before they start.

No service in Puerto Rico or any U.S. territory

This is the exclusion most likely to catch someone out. Cash App Mobile has no coverage within United States territories — Puerto Rico, the U.S. Virgin Islands, Guam, American Samoa and the Northern Mariana Islands are all named. AT&T's own network treats Puerto Rico and the USVI as domestic, and most plans that run on it include them, so a buyer reasoning from "it's on AT&T" will assume coverage that is not there. If anyone in the household travels to or has family in those places, this alone is disqualifying.

No international calling from the U.S.

Calls and texts made from the United States to other countries are not supported. Not metered, not pay-per-use — not supported. That is a harder line than most prepaid plans draw, and it is separate from the roaming allowance: Canada and Mexico are covered when you are physically there, with 10GB of data and 1,000 combined minutes and/or texts per billing cycle. Cash App describes that allowance as intended for travel rather than primary use, which is the usual language preceding enforcement against people who live near the border and use it daily.

How billing works

The first payment is taken at sign-up and the plan renews on that same date each month. The billing cycle itself does not begin until your number is set up, and service starts when the eSIM is installed. So the charge and the service can be a few days apart. Number transfer is supported and needs your account number, transfer PIN and billing ZIP code from your current carrier; skip it and a new number is assigned automatically.

Who it fits

A single line on a recent unlocked phone, used mostly in the fifty states, by someone who already lives in Cash App and wants one flat number on the bill. The no-credit-check, no-contract, no-store-visit path is genuinely low friction for that person. Everyone else — multi-line households, anyone with an older or locked phone, anyone who calls abroad, anyone with ties to Puerto Rico — is better served by an AT&T MVNO that has none of those three restrictions.