Refund claim by deductor under Chapter XIX requires challan details, declaration of non-duplication, and complete supporting records. Form No. 139 is the prescribed form for a deductor claiming refund of a sum paid under Chapter XIX of the Income Tax Act. It requires the deductor's identification and banking particulars, together with challan-wise details of tax deposited, statements in which the challan was utilised, and the amount of refund claimed. The form also contains a declaration that the amount has been deducted and deposited to the credit of the Central Government and will not be claimed again, and that the particulars furnished are true, complete and supported by records.