I don’t think tax returns are considered in the admission part of the decision process.
They may just be considered in the financial aid decision process, and you have to submit the FAFSA by Feb 15 anyway, so you can give the correct info then. However, since I’m not sure what part of the application you are talking about to begin with, you can always call and ask…but honestly I would not lose sleep over it. Sometimes it’s how you read these questions that is so confusing, so honest mistakes do happen. The only thing I can think of is maybe it has something to do with proving Maryland residency…? (thus my kids/I would have skipped that section so that’s why I am not sure what you are talking about…I seem to recall something like that now?)