If I need to claim milage as self emplyed after using my own car as a one off for business trip how and which category. I do not ususally use my own car.

You can claim mileage as a business expense, even for a one-off trip, Flex.

In QuickBooks Online (QBO), you can set yourself as a supplier to your business for this specific expense to accurately record a one-off mileage claim.

Follow the detailed steps below for guidance:

Step 1: Set up a Supplier profile for yourself.

1. Go to the Expenses tab and select the Suppliers section.
2. Create a new supplier profile using your name, and add an indicator to distinguish this record from any other personal transactions.
3. Select Save.

Set 2: Set up a mileage reimbursement expense account.

1. Go to your Chart of Accounts and create a new Expense account.
2. Choose the Auto or Travel detail type.
3. Give the account a unique name that's easy to identify.
4. Select Save and Close.

Step 3: Create a non-stock item for mileage.

1. Go to Products and Services.
2. Create a Non-stock item named Manual Mileage.
3. In the Description section, select I sell this product/service to my customers. Then enter a description.
4. In the Purchasing information section, select I purchase this product/service from a supplier. Then enter a description.
5. Link this item to the Mileage Reimbursement expense account you just created.
6. The Sales price/rate is the HMRC-approved mileage rate. This automatically calculates the amount when you enter the number of miles.

Step 4: Create a bill for your mileage claim.

1. Create a Bill.
2. Select the Supplier profile you just created.
3. Add the Manual Mileage item you created.
4. In the Qty field, enter the total number of miles for your one-off trip. The amount will automatically calculate based on the rate you set.
5. In the Description, add details of the trip.

If you have a business bank account, you can record a Pay Bills transaction to show the business "paying" you. Alternatively, you can leave the bill as unpaid if you're not physically transferring the money from your business account to your account.

Feel free to ask if you need clarification on these steps or help with any other tasks in QuickBooks Online.