Similar question here:
Review at end of June
June 2010 to June 2011 – 25K, Silver renewed.
July 2011 to April 2012 – 25K, Silver renewal qualified for 2 months prior to review date.
May 2012 - 6K,
June 2012 to May 2013 – 19K
From May 2012 to May 2013 I’ll have achieved 25K since I earned enough to renew the previous year’s Silver, but if my account is not reviewed until June 2013 the 6K in May 2012 will drop off. How will Skywards see this?
I have another trip I'm trying to schedule between now and the end of the year that could give me Gold, but struggling to fit it in so would hate to just miss out and shortly afterwards find myself losing Silver as well.