Time and Place for Filing
The Iowa S corporation return must be filed on or
before the last day of the fourth month following
the close of the S corporation’s tax year. For
calendar year filers, the due date is May 1, 2023.
If the S corporation is required to file a short period
return consisting of fewer than 12 months, the Iowa
short period return is due 45 days after the due
date of the federal short period return. Every S
corporation that owes no tax and does not file by
the original due date automatically receives a 6-
month extension of time to file after the original due
date, provided the return is filed within that 6-
month period. No extension request form is
required. If the S corporation owes tax on built-in
gains or passive investment income (see Part 5
below), a 6-month automatic extension will be
granted only if at least 90% of that total tax liability
is paid by the original due date of the return. Late filed returns are subject to penalty. For more
information, see the instructions for Part 6, lines 49
and 50 below.

Line 50: S corporations that do not owe Iowa tax
on built-in gains or passive investment income on
line 35 but that file their IA 1120S return after the
due date, including extensions, are subject to a
late filing penalty. For more information, see Iowa
Code section 421.27(1)(b) and Iowa
Administrative Code rule 701—10.6(2). If you are
filing your return late and do not owe Iowa tax on
built-in gains or passive investment income (line
35), complete the late filing penalty calculation in
Part 7, lines 55-60, and enter the amount from
line 60 on this line.