In September 2018, the Supreme Court confirmed that Aadhaar is compulsory for filing of income tax returns. The apex court maintained the validity of section 139AA of the Income Tax Act. This section was made effective from July 1, 2017. Section 139AA says that Aadhaar must be quoted in all PAN applications. It also says that every person who is eligible to obtain Aadhaar as per the Aadhaar Act, 2016, must mention Aadhaar while filing tax returns. PAN numbers without Aadhaar will be invalid. Therefore, every PAN holder who has an Aadhaar must link it on the income tax website.