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The first and clearly most influential large-scale implementation of eSignature was by the U.S. Internal Revenue Service. After several limited pilot studies, in 2001 taxpayers meeting certain requirements were able to file paperless [tax year 2000 returnsfor tax year 2000 returns complete with an eSignature. Through tax preparation software (such as Intuit's Turbotax) they were guided through selecting a five-digit PIN number and providing two specific items of data from their previous year's tax return. Selecting a PIN number and providing prior-year personal tax information served as an electronic signature for an e-Filed return. According to UncleFed's Tax Board 4,293,085 taxpayers signed their returns with self-select PINs in 2001.