Can I add custom mileage rates in the UK edition of Zoho Expense?

Yes, that can be done.

To add a custom mileage rate:

• Navigate to the Policies module on the left sidebar.
• Go to the policy for which you would like to add the mileage rate.
• Move to Mileage section. You will see the list of mileage rates set by the HMRC.
• Click the + add new rate option at the bottom of the page.
• Enter the new mileage rate by filling the text fields under the Mileage Rates section. (Date and mileage rate.)
• Select a vehicle type if necessary.
• Press Enter, and your new mileage rate will be added to the list of mileage rates.