Forward vs Spot Interest Rate Matrix Time Horizon This code uses the arbitrage free approach to construct spot/forward rates from the given rates. Zi denotes i-year spot rate, and fi,j is j-year forward rate starting in year i. In order to get the rate matrix filled, you need to specify one rate from each column, and the app will calculate the remaining rates. If more than one rate is entered in a column, the top rate will be used and the rest will be ignored. Adopted from CFA level II materials. Spot Rates: Forward Rates in 1 Year: