The expense categories in QuickBooks Self-Employed line up with the Schedule C tax form, info1389.
Hence, we cannot create custom expense categories within the program. You can browse the About SA103F Categories article for more information.
This is to ensure that your estimated taxes are accurate. Here are some references regarding the calculations and reports:
You can also visit this link if you have more questions about the program: QuickBooks Self-Employed Overview.
Get back to us if you have more questions or clarifications that are not mentioned on those links. Have a great day!