The Lake County Treasurer's office is accepting prepayments for tax year 2019 due in calendar year 2020 through Dec. 27. Prepayment amounts are limited to the tax amount due in 2019 as a maximum. Payments should be made by check, clearly identified as a property tax prepayment, and include your PIN number. Checks can be brought in person or mailed to theLake County Treasurer’s Office, 18 N. County St., Room 102 Waukegan, IL 60085.