Why you cannot find the exemption in the Income-tax Act
The reason the exemption is so hard to find is that it is not in the Income-tax Act at all. People search Section 10 for a sub-clause covering a UN salary and come up empty, and conclude either that it is taxable or that they have missed something. Neither is right.
A UN official's salary is exempt because a different law makes it so. India gave legal force to the international agreement on UN privileges, and that agreement, not the tax law, is what removes the salary from Indian tax. This matters in practice because it changes how you claim it: you are not pointing to a tax-code exemption, you are relying on a special statute and a treaty schedule, and the disclosure on the return has to reflect that. Once you know where the exemption actually lives, the confusion clears.
The UN (Privileges and Immunities) Act, 1947
The operative law is the United Nations (Privileges and Immunities) Act, 1947. Its Section 2 provides that the 1946 Convention on the Privileges and Immunities of the United Nations has the force of law in India, notwithstanding anything to the contrary in any other law. Within that Convention, Article V, Section 18(b) exempts UN officials from tax on the salaries and emoluments paid to them by the United Nations.
Because the exemption flows from the Convention given force by the Act, it applies to a UN official who is an Indian resident just as it does to any other, so a resident Indian working for the UN pays no Indian tax on the UN salary. The pension of a UN official is treated the same way, since it is part of the emoluments the exemption covers. CBDT Circular 293 of 1981 records the department's acceptance of this, which is useful to cite when you disclose the exempt salary on the return.
World Bank and IMF are different, and Indians are not exempt
This is the point that most needs care, because a lot of general advice wrongly lumps every international organisation together. The World Bank and the IMF do not run through the UN Act. Their exemptions come from their own Articles of Agreement, given domestic effect by the International Monetary Fund and Bank Act, 1945.
The crucial difference is a nationality carve-out. Under those Articles, the salary exemption applies only to officers and employees who are not local nationals of the country. So an Indian national employed by the World Bank or the IMF and taxed in India is not exempt on that salary, unlike a UN official, who is exempt regardless of nationality. This is a real and expensive difference: an Indian assuming their World Bank salary is tax-free the way a UN salary is can be badly wrong. If you work for the World Bank, the IMF, or a related institution, the exemption has to be checked against that specific organisation's rules and your nationality, not assumed from the UN position.
The limits: only the salary, only officials
Even where the UN exemption clearly applies, it is narrower than people treat it. It exempts the organisation salary and emoluments, and nothing else. Your Indian income sits entirely outside the exemption: rent from an Indian flat, interest on your deposits, capital gains on Indian shares or property are all taxable in the normal way. A common overreach is to treat the UN exemption as a personal tax holiday; it is not, it is limited to the UN pay.
The second limit is who is covered. The exemption is for officials of the organisation, not for independent consultants or contractors engaged by it. A person on a consultancy contract with the UN is generally not an exempt official, and their fees are taxable in India as professional income, often with the contract itself stating that local tax law applies. So before relying on the exemption, two things have to be true: the income is the organisation salary, and you are an official rather than a consultant.
A worked example: a UN officer and a World Bank officer in Delhi
Compare two Delhi residents. Anjali is a UN official earning a UN salary of about 60 lakh rupees, and she also has 6 lakh of rent from an Indian flat. Her UN salary is exempt under the 1947 Act and the Convention, so India taxes none of it; but the 6 lakh of rent is ordinary Indian income and is taxed normally. Her CA files her return showing the UN salary as exempt, with the Act and Circular 293 as the basis, and taxes the rent.
Raghav is an Indian national employed by the World Bank in Delhi on a similar salary. He assumes his salary is tax-free the way Anjali's is. It is not: the World Bank exemption under its Articles applies only to officials who are not local nationals, so as an Indian national he is taxable on the salary. His CA tells him this before he files, so he pays the correct Indian tax rather than claiming an exemption that does not exist and inviting a demand. Same city, same kind of job, opposite answer, because the organisation and the nationality rule differ.