Is a check for $983 that I received in December 2024 from my state attorney general collections department from a 2007 collections error they made considered income?

[donkincaid]

This is from the tax year 1998. The collections action was completed in 2007 when I made my final collections payment.

[Opus 17]

Generally not.  You are getting a refund of your own money.  It would only be taxable now if it was some kind of tax deduction back when.  (For example, if you deduct your property taxes, and the next year get a property tax refund, the refund will be a taxable reimbursement of a previous deduction.)