I think it depends on the company and thier arrangement. In the mi9ddle of the year a few years ago, my company (a really big one), switched from United to AA, They automatically switched me to AA Plat (I was flying about 50k per year), Since I did not make my 50k on AA the first year, I spoke with my travel department and they were able to have me be Plat the next year as well. They did this for me and some of my co-workers, who also missed out due to the mid year change. Last year was no problem earning it flying and this year I am 5000 miles from EXP, which when I go to NY in a few weeks, will move me up!