Check your return
As you fill in each page of your tax return, you'll receive an error message if you've missed completing something.
Once you've filled in your return, there's a further check on this page too. For example if you said at the start that you were employed, but haven't filled in the employment pages, you'll see an error message next to 'employment'. In this example there are 4 errors in the employment section that need to be corrected.
When you go to the employment section, you'll see a more detailed error message next to each of the four entries you need to correct.
You must correct all the errors before you can submit your tax return.