Form 26QB queries for joint property owners

Hi!, I purchased a flat from a private builder under construction linked instalment scheme in Gurgaon. The buyer seller agreement was executed in the year 2013 for a consideration of 4985661/- towards the cost of the flat. Now in the 2018, the builder has offered the possession of completed flat and given the final Price as 5800000/-. Do I need to deduct TDS on 800000 or the entire amount or there is no need of TDS as the initial agreement was for less than 50 lakhs. Best Regards