This rolling tier thing ...
 

Let's see if I've got it right:

1. I have to re-qualify (i.e., get my 75 nights) in a calendar year, Jan 1 to Dec 31.

2. If I don't make it (might not this year) I drop down to whatever level I did qualify for.

3. However, for being upgraded to a higher level of status, they use the rolling 12-month window, and as soon as I get the required nights, I'm kicked back up.

I'm asking because I might only get to 65-70 nights by the end of the year, but I should get the rest in January. I won't actually need the status during the interim, but I just want to make sure it comes back.

Is this how it works?

Close. You will need the 75 nights for the previous 365 days after February 28, 2009 as you will be Platinum until then. So if you were heavy on nights in Jan & Feb 2008, then there is a good chance you will not have 75 or more nights on or after March 1 when you return to Gold elite status and are eligible once again to attain Plat via the rolling tier. Rolliing tier may only be used to advance to the next status level, it cannot be used to maintain the current status level; so you have to drop back to Gold first before being able to advance to Plat via the rolling tier. Hopefully your return to Gold will be very short lived. FWIW, you may well be automatically retained as Platinum anyway, year before last I was and only had 53 nights; I had about 35 nights booked for the first 3 months of 2007 and would have gotten it after March 1 anyway. I hope that helped.

That's even better ... I had thought they might drop me on Jan 1. Should have the required night easy by Feb 28.

BTW, a friend of mine, who I turned on to Marriott, reports he was also continued as a plat even though he didn't have the necessary nights in, so I know it does happen.

But with the Feb 28 cutoff, I should be in perfect shape.

Thanks.

Just a few additions to what has been said. Your nights toward the renewal of your platinum status will be counted until December 31st. Your status continues until the end of February in order to get the new card out. Once an account has been downgraded it will be looked at every Monday when the system checks to see how many nights have been posted to each account in the last 12 months.

Several post have mentioned that accounts are not always down graded even when there have not been enough nights during the calendar year. This is most likely because of something we call tenure renew. Basically we look at the amount of stays a member has had over the last three years and renew the member’s status based on thresholds that show a pattern of long term loyalty.

Thanks for this little piece of extra info. Its nice to know a little more about why some have been able to keep their elite levels while some have not.

Imagine that.

Actual human beings look at your account and make a (presumably) rational decision based on the totality of your relationship with Marriott.

Would that other programs did the same. ^

I had back to back 100+ night years followed by a 50ish night year and kept my plat status. Very nice touch.

Is there an actual formula when calculating tenure renewal?

It's one of the peculiarities of the system, but you might be in even better shape if you let your Platinum lapse, but picked up the "75 nights in the last 365 days" Platinum the first Monday in March.

The reason? Renewing with 75 nights in CY 2008 would give you Platinum until end of February 2010 and then you'd have to stay another 75 nights in CY 2009 to qualify for CY 2010, but (at least as it used to be) getting picked up by the "rolling year" method on or after 1 March 2009 would extend your Platinum to end of February 2011! That's because when you qualify for Platinum (as opposed to "requalifying") you get Platinum for the rest of the year you qualified, plus the next year, plus the year after that through the end of February.

It makes sense, it's just that the result is sort of counter-intuitive when you barely miss requalifying and then have a slug of nights early on after you revert to Gold. Essentially most of the nights to qualify you for Platinum for the year 2010 occur in CY 2008 instead of 2009.