Can I continue to take only my benefits after my husband has filed for his own benefits or will Social Security automatically add in my (reduced) excess spousal benefits?
Scenario: July 2017 - wife is 62+1 and takes her own reduced benefits now or soon after. (no deeming as husband has not filed)
Mar 2020 - husband is 66 (FRA) and takes his benefits. (wife is now eligible for spousal benefits)
Aug 2021 - wife is 66+2 (FRA) and now files for full excess spousal which is added to her own reduced benefits.
While this may seem strange, wife's benefit at 70 will never exceed full spousal benefit and at 66 her own benefit will only be 40% of her full spousal benefit. So taking a hit on her own benefit will be "relatively" small but might be worth it depending on finances at that time.
Based on the new deeming rules passed by Congress last year (see: https://secure.ssa.gov/apps10/reference.nsf/links/02052016024404PM), the wife in the scenario above would be deemed to apply for reduced excess spousal benefits effective with March 2020 when her husband starts drawing. People born prior to 1954 were grandfathered under the new rules, and would have the option of waiting to apply for an unreduced excess spousal benefit.
One positive note is that the excess spousal benefit would only be reduced for the number of months between the entitlement date and the month of full retirement age (FRA) attainment, or roughly 13.2% in the above scenario.
If you haven't already done so, you may want to consider running the maximization software available on this website. That should help clarify your filing options so that you make the best possible choices.