If the future treaty that bans production of fissile materials for weapons is to require declarations of the existing fissile material stocks, it would have to include provisions to allow effective verification of these declarations as well as measures that would deal with the materials in active nuclear arsenals. These requirements may present a significant challenge for the future fissile material control agreement. This paper examines some practical challenges of including declarations of fissile material stocks in the treaty as well as solutions that could help address these challenges.