I'm not sure why it is so difficult to determine the amount of the premiums well before 12/31.  The insurance companies that I am familiar with provide the premium amounts well in advance.  However, in a worse case scenario, I would pick up eleven months of premiums and catch that twelfth payment the following year.  But I have to admit, it really bothers me that a licensed CPA would recommend to a client to back date a check.  I am disappointed that you would make such a recommendation no matter what the dollar amount is.