I just won £2,000 in a competition, is it tax deductible? How do I catogorise this transaction? I’m self-employed.

 Welcome to Community, @nimshi-k98-gmail.

I have an idea of how you can categorise winnings. Though you can categorise your winnings as Personal, I recommend consulting with an accountant for proper recording. They have more knowledge about Self-Employment accounting and help you which category to use. Mark personal for income that's not part of your self-employed business as "Personal", all are deductible.

You can learn more about categorising transaction at this guide: Categorise transactions in QuickBooks Self-Employed.

Additionally, here's a link that covers all tasks you can do when using QBSE.

Keep me posted if you still have questions or concerns. I'll be around to assist you. Have a great rest of the week.