federal pension reduction

I have a friend who lives in a retirement home without internet and limited mobility issues. He is retired civil service and remembers that there is a formula for calculating his taxable income from his pension. He thinks it is the result of a "pension reduction act," but can't find any information on it and can't remember what the formula is. He retired in 1999, and is not in a position to hire a tax professional. He always prepared his own taxes, but when he moved into the retirement facility, he lost all prior year tax records. 

Any help or direction to get help would be appreciated.