The fact is, recorded or not, once a deed is executed title to the property is transferred. Accordingly, the person who is named as the grantee, as the new owner, is responsible for all ownership obligations, including but not limited to, the payment of taxes. The fact is that a deed need not be recorded in order to be valid. However, recording a deed is advisable. A recorded deed notifies the world that as to who the true owner of the property is. An unrecorded deed is vulnerable to:Being lost/destroyed (in which event if the grantor dies or changes their mind there is no proof of ownership), Made invalid (if a new deed to a new grantee is recorded before yours), or Made subordinate to any future lien that may be placed against the property (in the case of a judgement lien, for example).  Bottom line, your mother is liable for all back taxes since the date of the deed.