What should you do if a tax lien is filed against you without you being informed in New York?
Unless there are exceptional circumstances, like you were in a comma for several years, your lack of knowledge of it is not a defense of any type. The process for these being made and filed is standardized and follows methods that are generally accepted as having been giving notice...things like attempts at mailing to your last known address, publication, etc.
However, that does not mean all is lost. If the basis for the judgment is truly faulty and you can prove it, you may (but not always - as failing to respond to their original notices in a timely fashion may make their claim irreversable), be able to have the State drop it. Otherwise, paying it (or settling it) with them is your only real alternative to having it satisfied.
Simply, contact the State Dept. of Tax, at any of their phone numbers or branches, to see what caused it and options you may have.A number for the Assesment Division is: 1-800-835-3554