stopping my service

What service? Internet? TV? Uverse? DirecTV?

AT&T does not prorate bills. You are billed through the END OF YOUR BILLING CYCLE.

If your billing cycle runs until May 4 - June 3 and you cancel on May 7, you are into the next billing cycle.

@mamafrog

Sounds like your service month is May 4 thru June 3. If so, the only way to avoid that bill was cancelling no later than May 3 which was the end of the prior service month. So you are not paying for most of June. You are not billed a month in advance, but at the start of your service month. If the service month starts May 4, then the bill produced and mailed May 5.

No matter what day you choose to stop using the service, you are still responsible for paying for the full service month. The stopped proration over a year ago. Here is the notice from 2018.

Please read this if you receive DIRECTV, AT&T U-verse® TV, AT&T Internet, AT&T Phone, and/or AT&T Fixed Wireless service(s). We want to remind you that you’re billed in advance for recurring service(s) and/or programming charges and applicable fees based on the terms of your current service agreement(s) with us. Starting January 14, 2019, subject to applicable laws, we’re updating your agreement(s) to include your recurring service(s)/programming charges and fees won’t be prorated if you cancel the above service(s) on any day other than the last day of your billing cycle. Your service(s) will continue until the end of your billing cycle but you won’t get a refund (prorated credits) for any remaining days left in your billing cycle. For products not listed above, refer to their terms of service for more information.

Questions about this change? Go to att.com/ProrationPolicy for more information and to see the revised section of your service agreement(s).