All depends how old the tax lien is.
For reference mid 2015, I had a 30/60 day late and a tax lien and a collection all from late 2010 and managed to get a mid-score of 720 so scorewise the lien doesn't prevent your getting a mortgage. I had 3.5ish years of positive history by that point and a highly optimized file, but it can be done.
Generally liens do need to be paid as I understand it, or the lien willpossibly attach to the house, which lenders hate.
