0001274737 2020-01-01 2020-12-31 0001274737 2020-06-30 0001274737 2021-03-12 iso4217:USD shares 2020 FY false 0001274737 10-K/A true 2020-12-31 --12-31 false 001-39049 EXAGEN INC. DE 20-0434866 1261 Liberty Way Vista CA 92081 (760) 560-1501 Common Stock, par value $0.001 per share XGN NASDAQ No No Yes Yes Non-accelerated Filer true true false false false 83400000 12669816 Certain information required to be disclosed in Part III of this report is incorporated by reference from the registrant's definitive Proxy Statement for the 2021 Annual Meeting of Stockholders, which proxy statement will be filed not later than 120 days after the end of the fiscal year covered by this Form 10-K.