As far as I know, only a government entity can put a tax lien on property – county for unpaid property tax, the state and feds for unpaid income taxes. I imagine what the HOA is doing is starting to foreclose its HOA lien, which it has by virture of unpaid fees. In California, this foreclosure is essentially like any other trustee sale. Once a notice of default is filed, the owner has 3 months to bring them current. After 3 months, a Notice of Sale is filed, and the sale can be held 21 days later. The sale may be held on the originally scheduled date, or may be cancelled if the owner pays the past due in full before the sale date. If the owner makes arrangements with the HOA to make payments on the past due, they may postpone it from month to month.

Check the owner’s name in the grantor-grantee index at the county to see if a notice of default has been filed. If it has, you’ll have about 4 months from the date it was filed.