Applicant with tax lien

I have an applicant (married couple) who want to purchase a home in my park. She has a $5000 tax lien filed against her. They say it is a state tax lien but there is now way to tell from the credit report.

I’m concerned about selling them the home on a note for fear the government could attach it. Home is $16,000 with 15% down. The were able to get auto financing. Any thoughts?