Plurals

Q. I was asked how to refer to more than one of a specific numbered form. For example, do you say “IRS Form 1040s” or “IRS Forms 1040”?

A. That depends. To refer to more than one copy of a form, add an s to the number—as in “three Form 1040s” or “five Form 1040-NRs.” To refer to two different forms, use plural “Forms”—as in “IRS Forms 1040 and 1040-NR.” The phrase “IRS Forms 1040” by itself would refer to multiple iterations of Form 1040 (e.g., Forms 1040, 1040-NR, and 1040-SR).

[This answer relies on the 17th edition of CMOS (2017) unless otherwise noted.]