10% of contract price (Excluding Provisional Sums & Daysworks) / shall commence in the next Interim Payment Certificate following that in which the total of all interim payments certified to the contractor has reached 30% of the Contract Price less Provisional Sums and Dayworks, and shall be made at the rate 20% of the amoumt of all interim payments Certificates until such time as the advance payment has been repaid always provided that advance paument shall be completely repaid prior to the time 80% of the contract Price has been certified for payment.