Can I review before I submit?

Yes. Before submitting your tax return you will be given the chance to review all tagged transactions and review each section of your return. When you tap the Review & Submit you will be asked to confirm a few final questions. 

On the final screen you will see an up to date tax calculation and be asked for your HMRC login details if you haven't already entered them. As well as this, the default option here is to submit a 'Test-in-Live' submission. This allows you to test the calculation before submitting for real. Nothing gets submitted until you give the final say so. 

You can also download a draft PDF report prior to submission by clicking the download icon at the top right of the screen.

Note that you can also file an amendment. So even if you were to file a live submission and then later discover an error, you can come back here and submit an amendment.

Read a step by step guide to submitting your tax return with untied here.