My full retirement age was 66 in 2014. I used the file and suspend strategy and took half of my spouses benefit for four years (and received COLAs based on that amount), then in 2018 began taking my own benefit at age 70 . I received the 8% per year in delayed retirement credits, which totaled 32% for waiting, which is what my current benefit is based on.... My question is, should MY benefit at age 70 have included the delayed credits PLUS COLAs (on my account) during the 4 years between age 66 and 70?
The short answer is yes. If you started drawing your Social Security retirement benefits at age 70 then your benefit rate should be 32% higher than your primary insurance amount (i.e. PIA x 1.32). A person's PIA is equal to their Social Security retirement benefit rate if they start drawing their benefits at full retirement age (FRA).
A person's PIA is automatically updated to reflect all Social Security cost of living (COLA) increases that occur after they reach age 62, regardless of whether or not they've claimed their benefits. So, your PIA undoubtedly reflects all of the appropriate COLAs. As long as you received the proper percentage of delayed retirement credits (DRC), you must be receiving your correct benefit rate.