Agencies have to bargain with unions over all matters affecting working conditions, with certain exceptions. The exceptions include: matters going to the heart of managing the enterprise, such as establishing the basic budget; matters already set by law or government-wide regulations; and classification matters.
It is important to remember, however, that AFGE represents its members on a whole range of subjects, such as GS pay increases, through lobbying. Thus, to say that an issue is outside the scope of bargaining does not mean the union can't effectively deal with it on behalf of its members.