One of the data-inputs for simulations of EIM's PRISMA-model is the input output (IO) table for the base-year of the simulation. PRISMA is an economic macro-sector model designed to produce results on SMEs in the Netherlands consistent with those produced by the current macro-sector model of CPB, Netherlands Bureau for Economic Policy Analysis. PRISMA is used for forecasting, scenario building and what-if analyses with respect to government policies and exogenous shocks. Its time horizon is 3-25 years. At present, the Dutch statistical institute does not publish an IO-table that simultaneously distinguishes firms by sector and firm size. As such a distinction is required for PRISMA it should be constructed separately. This paper presents the design of the table.