My husband is 69 and I am 59. We are both still working, however his salary in 2015 was the highest to date and will taper off in the next five years. Should he file for retirement benefits now? Will the percentage change in benefits will be large enough to warrant postponing for another year. Also, it is my understanding that the optimal time for me to file for spousal benefits is when I hit my FRA since I was born after 1954 and postpone my own retirement benefits or will I have been deemed to file for my own retirement benefits if I file for spousal benefits?

Sandy,
Your husband's retirement benefit will increase by an additional 8%, due to delayed retirement credits, if he delays taking it by one more year. You will be deemed to have filed for both your retirement and spouse's benefit when you file for either since you were born after 1 Jan 1954.
Best,
Mike