(2) It is mandatory for the applicants to mention either their ''Telephone number'' or valid. âť– The 15 digit acknowledgement no.Appearing on the acknowledgement receipt can be used for tracking status of application. Copy to be kept with application. Tax Invoice cum Acknowledgement receipt of PAN Application (Form 49A). An applicant will fill Form 49A online and submit the form. (b), If there are any errors, rectify them and re-submit the form.