Prepositions, conjunctions, and articles in the titles of IRS forms and publications are typically not capitalized; but this is not always the case. Sometimes these items are capitalized.
I decided to analyze the IRS’ use of capitalization in the titles of forms and publications. The IRS has a webpage where you can view all of their forms and publications. The following is a summary of the types of items included:
The most frequently used preposition in the titles is “for”. This term is used 1,138 times. It is not capitalized 97% of the time.
The next most frequently used preposition is “of”. This term is used 655 times. It is not capitalized nearly 100% of the time.
The conjunction “and” is used 601 times. It is not capitalized 99% of the time.
Interestingly, “with” is only used 70 times, but it is capitalized 61% of those times.
Below is a table that summarizes the statistics.