i am 69 and want to start collecting benefits in Sept. 2017. Can I get retroactive benefits to begin anytime in 2017?

Hi,

Assuming that you haven't already filed and suspended your benefits, you can claim benefits up to 6 months retroactively from the month in which you apply. Note, however, that you will not receive delayed retirement credits (https://www.ssa.gov/planners/retire/delayret.html) for any months for which you end up being paid.

Best, Jerry