An alert reader asked via email what to do about the Annunciation falling on a Sunday in Lent this year (Judica even - the beginning of Passiontide). Here's how I responded.
No - nothing trumps Lent, even the Annunciation. When the latter falls on a Sunday, it is transferred to the first free weekday after Easter.
LSB allows the supplanting of a Sunday in Lent, but this is indicative of LSB's general permissiveness toward widespread practice and should not be read as a suggestion of what the best practice might be. The Historic Lectionary's Lent is a logical progression and something more than just one Sunday is lost if one Sunday is replaced.
For our part, we observe Annunciation at our first midweek service after Quasimodo Geniti, which is the first week without privileged readings of its own. If you don't have midweek services, then it would be appropriate it include the collect for Annunciation after the collect for the Sunday of Lent on March 25. This, by the way, is one of the great arguments to have a regular midweek Divine Service: it's an outlet for the many important days in the Christian calendar that don't quite merit displacing a Sunday.