RCM on Loading & Transport Charges

I am doing Contract in Highway Department i Have given a cheque of Rs.14,00,000/- to transport agency but no gst  invoice or amount received from party the party ask us to pay 5% RCM in GST and ask to claim the paid RCM 5% at the same month is it possible or take the paid amount in same month and the tax is 5% or 18%