A Face-to-Face Encounter Documentation is only required for the initial certification.
See the following article for more information: https://www.cms.gov/Outreach-and-Education/Medicare-Learning-Network-MLN/MLNMattersArticles/downloads/SE1219.pdf
Often times, the following requirement is mistaken as a need for a face-to-face encounter:
https://www.cms.gov/Regulations-and-Guidance/Guidance/Transmittals/Downloads/R602PI.pdf
This basically shows that there is a need to get an estimate from the physician on how much longer the patient will require additional home health services (but not a face-to-face encounter).