Well, traditionally it was Feb 2nd ;)
While we "tone down" at the Epiphany Octave's end, 13th January,[the tree is just about had it by then!] we do not "end" Christmastide until the Feast of the Purification, 2nd February. That's the day we put away the Crib and bring down the last of the indoor decorations.Remember: 40 Days of Christmas goes with the tradition of 40 days for Lent and Eastertide!
Re: Feb 2nd.I can see good reason for changing it. For example, this year Feb 2nd falls after Septuagesima.
In response to:"Re: Feb 2nd. I can see good reason for changing it. For example, this year Feb 2nd falls after Septuagesima."No "change" was made for the end of Christmastide. It's still on 2nd February. Many a year the Purification takes place within Septuagesima, the rubrics of the Mass making the necessary changes adjustments for that.The fact is, Our Lady's Purification took place 40 Days after the Nativity. THAT's the feast we celebrate on Candlemas day! It's wonderful to have that last taste of Christmas as we rejoice with the Immaculata as did Simeon and Anna!