ITC of IGST paid during Customs Assessment

Sir, The custom department has made the assessment for the FY 2017-18, 2018-19 and 2019-20. The IGST has been deposited by the importer as per demand raised in the order. The assessment order is dated 20 January, 2020. Can we claim the ITC of the whole amount of tax paid in respect of all the financial years in our August GSTR-3B. And if yes, then where it to be claimed whether under import or any other ITC column.