The IRS has suspended the mailing of three notices – the CP501, the CP503 and the CP504 – that go to taxpayers who have a balance due on their taxes. Although the IRS continues to make significant reductions in the backlog of unopened mail that developed while most IRS operations were closed due to COVID-19, this temporary adjustment to processing is intended to lessen any possible confusion that might be associated with delays in processing correspondence received from taxpayers.