Qualifying nights for Milestone

[ClubSmed]

I can’t seem to find the answer to this on the IHG site, so am asking here.
How do nights get allocated for stays that span the year end?

I am 2 nights short of a milestone, but have a qualifying stay 30th Dec to 4th Jan.
Would the nights within this stay be allocated to the year they belong in, or to the year that the stay ends?
If it’s the former, which year would the 31st/1st night fall into?
Thanks in advance for any help and insights.

[John]

31st night/1st morning credits to the new year.

Not sure about the 30th night/31st morning, it may also go into the new year. If you need it to credit to the old year you may wish to play it safe and book a different hotel for that night.