Interstate Power & Light Co., a unit of Alliant Energy Corp., plans to sell $200 million of 10-year notes, a person familiar with the transaction told Bloomberg. The notes could pay 105 basis points to 110 basis points more than similar-maturity Treasuries, said the person, who declined to be identified because terms aren’t set. A basis point is 0.01 percentage point. Proceeds will be used to fund the redemption of 6.75 percent notes due in March 2011, the Cedar Rapids-based company said Monday in a regulatory filing that didn’t specify the size, timing or maturity of the sale. Bank of America Corp. and Wells Fargo & Co. are managing the sale, according to the filing.