The IRmark on a tax return will change if you:

• make changes to the entries on the return
• remove a figure and re-enter it as it was before.

The IRmark shouldn't change if you amend anything outside of the return, such as an email address or filing credentials.

Please note that when a software update is done, the IRmark is likely to change. We therefore recommend that you keep a PDF copy of all documents before attempting submission (or just after submission with the FBI receipt attached).