I have a past tuition balance from school and it's now in a collections agency. Will this affect this year's tax return?

[IreneS]

If you are talking about a past-due debt to the school, probably not.  If the school's collection agency pursues collection further, the likelihood is that they will go to court to garnish your wages (if you are working).

If you mean that you have defaulted on a federal student loan, the Department of Education may send the Treasury a request to seize your tax refund to put toward defaulted loans.  Fortunately, the IRS is legally required to notify you by mail of their proposal to offset your taxes and allow you some time to respond.  So if you haven't heard from the IRS this year's refund is probably safe.

You really should try to make some payment arrangements with the school so that this doesn't ruin your credit standing.