Question: How should I code for a four-hour chemo? Should I put modifier 59 (Distinct procedural service) on each code? Maine Subscriber Answer: If you perform a four-hour chemo administration, report 96413 (Chemotherapy administration, intravenous infusion technique; up to 1 hour, single or initial substance/drug) for the first hour and +96415 x 3 (- each additional hour [list separately in addition to code for primary procedure]) for the next three hours. Furthermore: Because you unit-bill for these -- and because 96415 is an add-on code -- no modifier is necessary. -- The answers for You Be the Coder and Reader Questions were reviewed by Cindy C. Parman, CPC, CPC-H, RCC, co-owner of Coding Strategies Inc. in Powder Springs, Ga., and past-president of the American Academy of Professional Coders National Advisory Board.