My husband Social Security Benefit at 70 years old is about $3800, mine is $1000.
My pension from CalSTRS is about $525 a month.
We are divorcing.
Question: If I accept his social security do I still have to pay Windfall elimination to the Social Security? How much would it be?
You wouldn't 'pay windfall elimination' to Social Security because that's not how the Windfall Elimination Provision (WEP) works (https://www.ssa.gov/pubs/EN-05-10045.pdf). Assuming that your earnings on which your CalSTRS pension is based were exempt from Social Security taxes, what would likely happen instead is that your own Social Security retirement benefit rate would be reduced due to WEP, and any spousal benefits for which you qualify would likely be reduced by 2/3rds of the amount of your CalSTRS pension due to the Government Pension Offset (GPO) provision (https://www.ssa.gov/pubs/EN-05-10007.pdf).
For example, say Mary receives a monthly state government pension of $600 based on her earnings that were exempt from Social Security taxes. Mary is also eligible for a Social Security retirement benefit based on her other work history, and her full retirement age rate or primary insurance amount (PIA) is $1000 before considering WEP. However, because of WEP Mary's PIA is calculated using a less generous formula that reduces her PIA to $700.
Mary's husband is drawing his Social Security retirement benefits and his PIA is $2800, so if Mary files for benefits her unreduced excess spousal rate would be calculated by subtracting her PIA from 50% of her husband's PIA. So, in this example, Mary's potential unreduced spousal rate would be $700 (I.e. $2800/2 - $700). However, due to the GPO provision, Mary's state government pension would result in her spousal amount being reduced by $400 (i.e. 2/3rds of $600). Therefore, if Mary filed for her benefits at full retirement age (FRA) she would be paid her full WEP reduced PIA of $700 plus a spousal benefit of $300 for a combined rate of $1000. However, if Mary files for benefits prior to her FRA both rates would be reduced for age, resulting in a lower combined amount.
If you've been married to your husband for at least 10 years and get divorced, you could likely qualify for divorced spousal benefits (https://www.ssa.gov/OP_Home/handbook/handbook.03/handbook-0311.html). Divorced spousal benefits are paid at the same rate as spousal benefits, so Mary's benefits in the above example would be the same even if she qualified for divorced spousal benefits as opposed to spousal benefits.
If you were born prior to January 2 1954 you could potentially file just for spousal or divorced spousal benefits only at your full retirement age without also filing for your own retirement benefits, but that probably wouldn't help you. That's because it doesn't sound like your own Social Security retirement benefit rate would exceed 50% of your husband's PIA even if you waited until age 70 to claim your benefits. And, you probably wouldn't be due a higher total monthly amount if you received just spousal (or divorced spousal) benefits only instead of a combined benefit based on both your own benefits and an excess spousal/divorced spousal benefit.
Our software is fully programmed to handle cases involving both the WEP and GPO provisions, so you may want to strongly consider using our software to compare your options and determine your best strategy for claiming benefits.