If one player has their clock down to 5 minutes and per the rules no longer notates their moves, if their opponent has more than 5 minutes left, are they also not required to notate their moves, or do they have to notate their moves until they too only have 5 minutes left?
Thanks in advance.
15C. Scorekeeping in time pressure, sudden death time control. If either player has less than five minutes remaining in a sudden death time control, both players are excused from the obligation to keep score. A scoresheet is not required to win on time in a sudden death control (13C).
Thank you very much. 
updated 15C rule:
15C. Scorekeeping in time pressure, sudden death time control. If Either Player has less
than five minutes remaining in a sudden death time control and does not have additional time
(increment) of 30 seconds or more added with each move, both players are excused from the
obligation to keep score….
TD TIP: Only players in games with increment time controls of 30 seconds or more and
using properly set increment capable clocks are required to keep score at all times,
even in the last five minutes of any time control period. Players using improperly set
increment clocks or non-increment capable clocks, even those clocks adjusted for an
increment time control, are regulated by rule 15C.