How can I remove unread letters from MyTax’s Tasks?

The Tasks tab shows how many letters there are that you have not read yet.
Click See decisions and letters below “xx unread letters”.

This will take you to the Decisions and letters page where the Mailbox is. All unread letters can be found in the Mailbox. Select Move all to archives. This way, you can remove the unread letters both from your mailbox and from Tasks. If you need to find these letters later, you can go to Archives on the Decisions and letters page.

Please note that the Tasks tab only shows the unread letters that are in the Mailbox. After you open a letter to read it, or after you move any of them to Archives, they disappear from Tasks.