I receive a state pension and a federal pension (FERS). I have 28 years of substantial earnings. Will my social security benefit be reduced because of the windfall elimination provision if I have 28 years instead of 30 years of substantial earnings but I was a federal worker hired in September 1987?
If you didn't pay Social Security taxes on at least some of the earnings on which your pensions are based, then yes your Social Security retirement benefit rate may be reduced due to the windfall elimination provision (WEP). However, if you have 28 years of 'substantial' earnings, the reduction should be relatively minor. For a list of what is considered as substantial earnings, see page 2 of this Social Security publication: https://www.ssa.gov/pubs/EN-05-10045.pdf.
The maximization software available on this website handles WEP computations, so you may want to use it to determine the benefit rate you can expect to receive, as well as your best filing strategy.