Sorry to hear about your offset problem. There are a number of factors used in making the offset decision, and you may still have facts on your side. It is normally applied against widow
's or survivor benefits
(if you are claiming on your spouse
's earnings history). You did not state this in your question, but this may account for the offset application to you and not to people you know.
You will be able to make your argument at SSA appeals. http://www.ssa.gov/pubs/EN-05-10041.pdf is the SSA appeals brochure for review.
http://www.ssa.gov/pubs/EN-05-10007.pdf is the SSA offset explanation page. The offset is applied to widow's or widower's benefits to avoid double dipping. The offset will apply to you, but not to others who have both TVA and their own SSA earnings/benefits to draw on. The offset is 2/3 of your government pension.
If this is instead a benefit reduction due to the Windfall Elimination
Provision, the calculation of the offset due to work not covered by social Security is more complicated, and is based on your work history, which again could explain why you may be subject to WEP and others you know are not.
http://www.ssa.gov/pubs/EN-05-10045.pdf is the link to the SSa review of WEP, including calculation of the offset (there is a chart that shows a 24 year service history equates to exactly a 60% reduction).
There are some exceptions to the WEP rules, also listed on that sheet. If any exceptions apply to you, the appeals process mentioned earlier will still apply.
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