The State Constitution limits how much the Legislature can spend from tax revenues. The administration’s 2018-19 budget proposal reflects increased “room” under this limit—essentially spending capacity—of roughly $6 billion over June 2017 levels. Notably, the administration revised its approach for estimating costs to comply with federal and court mandates, which are excluded from the limit. We find that the mandates approach is inconsistent with the implementation of the spending limit because the administration reflects costs from any mandate whereas only costs resulting from mandates imposed after 1978-79 should be excluded from the limit. We recommend the Legislature direct the administration to revise its approach going forward to be consistent with the limit, which conceivably could increase or decrease room under the limit. In addition, we make several additional recommendations that would reduce room under the limit by several billion dollars.