I am 63 (born Dec. 1953). I have 40 quarters of soc. sec. earnings and would received approx. $1800/mo at full retirement age on my own account. My husband (born July 1950) started taking his soc. sec. at age 62. His monthly benefit before Part B is $1850. We also have an adult child in our household disabled at birth (down syndrome) Born in 1985. She receives a child's benefit of $1257/mo. What is my best strategy for when to file and what to file for? I can wait until full retirement age (66) or later, but I don't want to leave money on the table unless it affects my future benefit.
That's a complicated question given your family circumstances. Normally, your best option would be to file for spousal benefits only at age 66, and then file on your own record at age 70. That still may well be your best option, but your entitlement to spousal benefits would almost certainly result in a reduced benefit rate for both you and your daughter due to the family maximum provision (https://www.ssa.gov/OACT/COLA/familymax.html). Still, the total amount payable to you and your daughter would be more than what she currently receives by herself.
The family maximum should no longer be a problem once you start drawing on your own record, be that at age 70 or before then if you choose to start taking your own benefits sooner. As I say, though, it's complicated. Fortunately, the maximization software available on this website is programmed to handle all of the variables involved with your family situation. You should strongly consider using the software to help you decide on your best course of action.