Buying a property (house and lot) Deed of absolute sale only. How to process this? and is it okay?

Hello po. I want to buy a property pero deed of absolute sale only. Last 2013 pa daw ito niya nabili pero hindi na process ang registration sa Bir and municipal. (No CAR) hindi din nabayadan ang capital gains tax sa deed of sale na inexecute niya with the first owner.

is this safe? someone told me about deed of assignment, kaso hindi ko alam magkano at ano ano ang lalabas na fees na kailangan ko ishoulder pa. Any advice? or work around po. Thank you