This article explains the process behind estimating a National Education Cost Model (NECM) and generating from that model projections of per-pupil costs to achieve 2016 national average outcomes (reading and math grades 3 to 8) across all districts in the United States, from 2019-20 to 2020-21. This article is a follow-up to a preliminary report prepared in 2018 in which the authors made a first attempt to estimate a National Education Cost Model using methods most often applied to individual states (Baker, Weber, Srikanth, Atzbi, Kim, 2018). Here, the authors have expanded on this process, to develop a three-step method from an estimated cost model using district level data on approximately 10,000 districts per year from 2009 to 2016, to a simulation of estimated costs for over 13,000 districts for 2019 through 2021. That process involves the following steps to be explained in detail in this article: Step 1: Estimating a National Education Cost Model to historical district level panel data with missing data; Step 2: Estimating a set of parsimonious weighting factors that approximate the cost model estimates with more easily updated, limited measures, covering all districts; and Step 3: Developing a formula simulation to apply to current and future district level data, complete panel.