I have empty bank accounts that I no longer use. It's unclear to me if I should report those accounts on form 8938.
According to IRS.gov, you have to report empty foreign bank accounts on Form 8938 (mirror) “Statement of Specified Foreign Financial Assets". From https://www.irs.gov/businesses/corporations/basic-questions-and-answers-on-form-8938#ReportQ2 (mirror):
Q2. If I have to file Form 8938, am I required to report all of my specified foreign financial assets regardless of whether the assets have a de miminis maximum value during the tax year?
If you meet the applicable reporting threshold, you must report all of your specified foreign financial assets, including the specified foreign financial assets that have a de minimis maximum value during the tax year. For exceptions to reporting, see Exceptions to Reporting on page 6 of the instructions for Form 8938 (mirror).
I'll first note that I'm not a US citizen or resident, so others may be better qualified to answer.
However, having found a copy of the form, part VI, question 4 asks for the "Maximum value of asset during tax year (check box that applies)" and the first box is labelled "$0–$50,000", suggesting to me that empty accounts should be included.