A homebuyer is questioning the legality of their builder demanding 12 months of prior maintenance charges and significant society formation fees before possession of their new flat. While these charges can be common, they may be unlawful if not clearly stated in the sale agreement. The advice suggests checking the agreement, refusing to pay if undisclosed, and potentially escalating the issue to RERA or a consumer forum if the builder insists. It also highlights the builder's responsibility to maintain the property until handover to the residents' association.