We told all our clients last year to pay in December too, because that is when IL 4th estimate is due.  But we have hundreds of 1120-S Corps and it is difficult to for us to have that many conversations.  The client letter shows incorrect dates, which makes it very confusing to the client.

What is ironic is ProSeries changed the 2021 letter to have the correct due date, sometime well after tax season.  That is how we first became aware of the error, when we were preparing extended returns.  We scrambled to call or email all our clients to let them know.  Now this new year 2022 product has reverted back to having the incorrect due date.