Why wont it deduct my 20% self assessment tax when I invoice??

Thank you for taking the time to post here in the Community, @midhurstscott-gm. Here’s what I can do to help you.

To isolate the issue, we can do a browser troubleshooting.

Here’s how:

1. Restart your browser.
2. Use other browser like Incognito.
3. Clear your browser’s cache and browsing history.

 
If the same issue persists you can contact support.
 

In case you have other concerns/query. You can comment down below. We're always right here to assist you. Keep safe!