I was at my wit's end as the owner of a wireless family plan — responsible for splitting the bill fairly each month as new charges came in. I was ready to tell everyone to get their own plans as I could not keep up with the constant changes and manual math.

Then I wrote a prompt and handed the work to an AI chatbot (ChatGPT, Claude, or similar). Paste in your carrier's PDF bill with this prompt and it will break up the bill for you based upon the rules you provide.

This prompt works flawlessly with AT&T. The names, groupings, and wearable assignments are specific to my plan, but the logic should transfer to your plan or other carriers with minor tweaks.

The prompt

Split the attached bill by each person's mobile phone (Kevin, Doug, Warren, Linda, Diane, Carol-Ann, Stephen) using the following logic:

- Account charges are split evenly across all phones.
- Group charges are split evenly across all phones.
- Individual charges belong to the individual.
- For International Day Pass charges: compute the average cost per day across the entire bill, then add (number of days that person had a charge) × (averaged rate) to their total.
- For wearable charges: compute the average cost per wearable, then assign to Kevin, Kevin, Carol-Ann, and Diane (Kevin is assigned to 2 wearables).
- Verify that the sum of everyone's portion equals the total bill amount.

Group and relabel the portions as follows:
- Kevin → Kevin/Giada
- Diane + Stephen → Mom/DadC
- Carol-Ann → CA
- Linda + Warren → Mom/DadO
- Doug → Doug

Produce a summary in this format:
{Label}: ${amount} ({item} + {item} + ...)
Where {item} can be phone, wearable, international usage, long distance, phone installment, etc.

Examples:
Kevin/Giada: $1.11 (1x phone + 2x wearable + international usage)
Mom/DadC: $2.22 (2x phone + 1x wearable + international usage)
CA: $3.33 (1x phone + 1x wearable)
Mom/DadO: $4.44 (2x phone)
Doug: $5.55 (1x phone + phone installment + long distance)

Customizing for your plan

Swap the phone names, group labels, and wearable assignments for yours. The International Day Pass and wearable rules are the fiddly parts on AT&T — if your carrier handles those differently, adjust those bullets and leave the rest alone.