Congressional Budget Office Cost Estimate: H.R. 51, Washington, D.C. Admission Act [open pdf - 256KB]
This is the Budget Office Cost Estimate as ordered reported by the House Committee on Oversight and Reform on April 14, 2021. From the Bill Summary: "H.R. 51 would admit the city of Washington, D.C., as the 51st state with the name of the State of Washington, Douglass Commonwealth. The new state would comprise all of the land currently included within the city's boundaries other than federal land as outlined in the bill. That excluded property, primarily the area around the National Mall, would be named the Capital. The new state would be provided with two U.S. Senators and one Member of the House of Representatives. Finally, the bill would outline new responsibilities for the state and establish a process for transferring certain powers from the federal government to the new state."
Congressional Budget Office: http://www.cbo.gov/