Larry, My wife will be 66 in April, 2017 and will still work full time as will I. She'll be eligible to receive SSA benefits based on her earnings record that will be substantially less (about 50%) than mine. I reach 66 in January, 2018, but plan on waiting until age 70 to maximize my SSA benefits. Based on what I've read here, it would appear that one strategy might be to have her file for her own benefits at age 66, have me file for spousal benefits when I reach 66 and then file for my benefits at age 70, at which time she would be entitled to a spousal benefit greater than what she will have received starting at age 66. In the meantime we will have collected her benefit at the lower amount for 4 years and my spousal benefit for about 3.25 years. At age 70, I would file to collect my higher benefit based on my earnings record and she then (I hope) would be eligible to collect a spousal benefit based on half my age 70 benefit, a few hundred higher than her age 66 benefit. Is my analysis fundamentally correct? Also, do I need to wait until I reach age 66 to get the full spousal benefit or could I get it when she files in April, 2017? Our goal would be to collect something for the years leading up to my turning 70 while we are both still working.
Your analysis is not entirely correct. Spousal benefits are calculated based on 50% of the worker's full retirement age benefit rate, regardless of whether or not the worker waits until age 70 to start their benefits. In other words, your wife can't get half of your age 70 benefit rate as a spouse.
Regarding your second question, you cannot file for just a spousal benefit until you reach age 66. If you file for a spousal benefit before then, you'll be deemed to have also filed for reduced benefits on your own record.
You still may want to consider your original plan, though. Your wife could still apply for her benefits when you reach age 66 in order to allow you to file for spousal benefits only at that time. Then you could switch to your own record at age 70, at which time your benefit rate will be 32% higher than if you started them at age 66. However, unless your wife's full benefit rate is less than 50% of your full retirement age rate (not 50% of your age 70 rate), she won't be eligible for any additional spousal benefits.
You should probably consider running the maximization software available on this website. That would help you determine the best filing strategy for both you and your wife.