@Wdtax20
According to the Massachusetts Department of Revenue's Tax Filing Season Frequently Asked Questions page, they'll adjust affected tax returns for most taxpayers who already filed, and no amended return will be needed:
Do not file an amended 2020 return before you hear from us. DOR will send a communication to all taxpayers who previously filed a 2020 income tax return reporting unemployment income and will adjust tax returns automatically for most taxpayers who meet the criteria for the unemployment deduction.
