The IRS announced that they will start sending out balance due notices again after they had suspended the mailing of these notices during the pandemic. The Balance Due Notices are know as the "500" Series of Notices which include (CP501, CP503 or CP504). Initially the IRS was mailing these notices out during the start of the pandemic but they were not able to process the written responses from the taxpayers. So the service temporarily stopped mailing these notices to taxpayers. The IRS has significantly worked through the backlog of opened mail that they can know start to mail out notices again. 

The CP501 notice alerts a taxpayer that they still have a balance due and the options available to pay the past due balance. The CP503 notice alerts the taxpayer that they have not responded to the prior notices from the IRS and the service may file a federal tax lien against the taxpayer. The CP504 notice alerts the taxpayer that they must pay their balance immediately or their state refund maybe levied. 

Taxpayers who were impacted by the pandemic may qualify for relief from penalties based upon 'reasonable cause' if it can be established that the taxpayer made an effort to comply with the law but was unable to meet their obligations because of circumstances beyond their control.