Certificate of residence requirements govern furnishing Form 10F particulars and applying for a residence certificate for treaty relief. Rule 21AB requires assessees claiming relief under agreements in sections 90 and 90A to provide particulars in Form No. 10F-including status, nationality or place of incorporation, tax identification or equivalent identifier, period of residential status, and overseas address-and to retain and produce supporting documents on request; residents seeking a residence certificate must apply in Form No. 10FA, and the Assessing Officer may issue the certificate in Form No. 10FB.