When the pick-up amount reaches zero, “EP USED” will be printed in the pick-up block on your 1099-R. This usually occurs within a few years after the date of retirement so enter $0 in box 17, if there is an entry in Box 15, and box 16, otherwise leave it blank.
Source: http://www.sra.state.md.us/Participants/Retired/Downloads/Newsletter/Retiree_Newsletter-2018-01.pdf