We will all find out about that if and when the proposed tax law change passes. Right now the Senate is debating a number of changes to the 3rd stimulus bill. if and when they pass anything, then there will be guidelines as to how and when the change will be implemented.
Nothing has changed concerning the unemployment compensation. No legislation has passed nor any changes to the tax code.
When and if the legislation passes the IRS has to write the regulations and the procedures after passage.