Whether you are eligible for Aadhaar or not is important as this determines whether or not you have to compulsorily quote it for filing your tax return, applying for PAN and for multiple other financial transactions where it has been made mandatory by law. Essentially, the laws regarding compulsory quoting of Aadhaar and linking to PAN only apply if you are a resident as per the Aadhaar Act There is a lot of confusion among people regarding who is eligible to obtain Aadhaar as amendments in the last budget have made financial life without one difficult.The budget presented in February this year made amendments in law vide Section 139AA in the Income Tax Act. As a consequence, from July 1, 2017, it has become mandatory to quote your Aadhaar number or Aadhaar enrolment ID (in case you have applied for Aadhaar but not received it) while filing your income tax return and when applying for PAN. It has also become mandatory to link your Aadhaar with your existing PAN even if you don't file your ITR.The question arises who is eligible to apply for Aadhaar? Are Non-resident Indian (NRI) or Foreign nationals living in India also eligible to apply for Aadhaar?The Aadhaar Act, 2016 states, "Every resident shall be entitled to obtain an aadhaar number by submitting his demographic information and biometric information by undergoing the process of enrolment."The Act further defines residency as, "An individual who has resided in India for a period or periods amounting in all to 182 days or more in the 12 months immediately preceding the date of application for enrolment."Himanshu Sinha, Partner, Trilegal says that in layman terms, it can be said that if you are applying for Aadhaar today, you have to go back one year from the date of application and assess if you have spent more than 182 days in India.This means that it does not matter whether you are an NRI or foreign national, if you have stayed in India for more than 182 days, you will be eligible to apply for Aadhaar, says Sinha.However, the Act does not mention whether the date of arrival or departure is taken into consideration and/or a half day is taken into consideration while calculating minimum number of days required to stay in India, he adds.One should not confuse Aadhaar residency definition stated above with the one mentioned in the income tax laws. The Income Tax Act defines an individual as a resident if in a financial year (1 April - 31 March), he has stayed in India for more than 182 days. On the other hand, under the Aadhaar Act, there are no specific dates defining a year.The Aadhaar Act has clarified that even if you're holding an Aadhaar or applied for one it does not mean that you have received Indian citizenship.Aadhaar is a 12-digit identification number issued to an individual after the receipt of demographic information such as address, date of birth and biometric information such as iris scan, finger prints etc.It is a random number which has no relation to any personal details of the person.Aadhaar is slowly becoming mandatory for a number of things e.g. doing banking transactions above Rs 50,000, getting benefits under government social security, subsidy schemes etc.Section 139AA of the Income Tax Act states that every person who is eligible to receive Aadhaar number must quote the same while filing his income tax return. It further states that every person who is having PAN and is eligible to obtain Aadhaar or already has one must link the two to avoid PAN being invalid from a date to be notified by the government.However, CBDT in its notification dated May 11, 2017 has exempted certain categories of individuals provided they do not hold Aadhaar and haven't applied for one. These are:(i) Non - Resident Indians (NRI) as per Income Tax Laws(ii) Not a citizen of India(iii) Age more than 80 years or more at any time during the tax year(iv) Residents of states of Assam, Meghalaya and Jammu & KashmirAn individual is not under the purview of section 139AA if he or she is not a resident as per Aadhaar Act.If your residency status changes in a particular tax year say, from NRI to Resident, then you will be required to quote Aadhaar number for filing tax returns.The Supreme Court order regarding linkage of PAN and Aadhaar provides relief only to those who have PAN but not Aadhaar.However, if you are going to file income tax return after July 01, 2017 then you are required to quote your aadhaar number (except for those exempted as mentioned above) which will inevitably require you to link your PAN with Aadhaar.