The UEFA Champions League titleholder is guaranteed a place in the groupstage even if it does not qualify for the competition through its domestic championship.
a) If the titleholder comes from an association entitled to four places in the
UEFA Champions League and qualifies for the UEFA Europa League
through its domestic competitions, the lowest-ranked club of the
association’s UEFA Champions League representatives is automatically
transferred to the UEFA Europa League (into the latest possible round
where there is a vacancy). In this case, the number of places to which the
titleholder's association is entitled in the UEFA Champions League and
the UEFA Europa League does not change.
b) If the titleholder comes from an association entitled to four places in the
UEFA Champions League and does not qualify for the UEFA Champions
League or UEFA Europa League through its domestic competitions, the
lowest-ranked club of the association’s UEFA Champions League
representatives is automatically transferred to the UEFA Europa League
(into the latest possible round where there is a vacancy). In this case, the
association of the titleholder is entitled to one additional place in the
UEFA Europa League.
c) If the titleholder comes from an association entitled to fewer than four
places in the UEFA Champions League and qualifies for the UEFA
Europa League through its domestic competitions, it is entitled to play in
the UEFA Champions League in addition to the association’s other UEFA
Champions League representative(s). In this case, the combined number
of places to which the titleholder's association is entitled in the UEFA
Champions League and UEFA Europa League does not change.
d) If the titleholder comes from an association entitled to fewer than four
places in the UEFA Champions League and does not qualify for the
UEFA Champions League or UEFA Europa League through its domestic
competitions, it is entitled to play in the UEFA Champions League in
addition to the association’s other UEFA Champions League
representative(s). In this case, the association of the titleholder is entitled
to one additional place in the UEFA Champions League.