This guidance provides recommendations to applicants seeking licensure under section 351(k) of the Public Health Service (PHS) Act of a proposed biosimilar or proposed interchangeable biosimilar for fewer than all of the reference product’s licensed conditions of use. This guidance also provides recommendations on the submission of a supplement to a licensed 351(k) biologics license application (BLA) seeking to add a condition of use that previously has been licensed for the reference product to the labeling of a licensed biosimilar or interchangeable product, including considerations related to the timing of such submissions.