This is more of a rant than a call for help; the IRS is bad at writing instructions in a clear, unambiguous way. The instructions for 1040 Schedule B say that filing Schedule B is required if "You had over $1,500 of taxable interest or ordinary dividends." I tend to interpret this as meaning that Schedule B is not required unless you had over $1500 of interest, or over $1500 in dividends. (i.e., if you had $1000 in interest income and $1000 in dividends, Schedule B is not required--the $1500 threshold applies to each category, not to the combined total.)
However, I did some searching online to try and verify my interpretation, and found at least two sources -- one from a major tax software site, and one CPA website, that say it actually is based on the combined total (interest + dividends). I found at least one other online source that supports the first interpretation that it applies to each category individually (interest, dividends) not the combined total.
If the IRS meant for this criteria to apply to the combined total, they should say "Schedule B is required if your combined total of taxable interest and dividend income exceeds $1500."
If the first interpretation is correct, the instructions should say "Schedule B is required if you had taxable interest over $1500, or ordinary dividends exceeding $1500."
It just seems lazy to leave it potentially open to misinterpretation.