We can predict this because we know the base rate for farmland for tax bills in 2021. The base rate is the starting point for the assessment of farmland. The state’s Department of Local Government Finance applied its formula to six years of data on corn and soybean prices, land rents, interest rates and costs, and came up with $1,280 per acre. That’s 18 percent less than this year’s base rate of $1,560. This value is adjusted for soil productivity and other factors to come up with the assessed value for each acre.