Chapter IV - Computation of Total Income
Section 66
Section 66: interpretation (definitions for Part D of Chapter IV)
Section 66 supplies 40 definitions for Part D of Chapter IV, which governs profits and gains of business or profession. Apply each definition to the provision using that term, including any expressly limited purpose or cross-reference. A definition can affect eligibility, classification and computation; it does not itself grant a deduction.
On this page
Need advice on Section 66?
This article is for general information. Refer to the Income-tax Act, 2025 as amended by the Finance Act, 2026 and the Taxation and Other Laws (Amendment) Act, 2026 for the official provisions. If you need professional advice for your situation, contact Bizeneed.
Statutory text
Bare law
For the purposes of Part D of this Chapter,—
(1) “agreement”, for the purposes of section 26(2)(h), includes any arrangement or understanding or action in concert,— (A) whether or not such arrangement, understanding or action is formal or in writing; or (B) whether or not such arrangement, understanding or action is intended to be enforceable by legal proceedings;
(2) “banking company” means a company to which the Banking Regulation Act, 1949 (10 of 1949) applies and includes any bank or banking institution referred to in section 51 of that Act;
(3) “commission or brokerage” shall have the meaning assigned to it in section 402(7);
(4) “commodities transactions tax” and “commodity derivative” shall have the same meanings as respectively assigned to them in Chapter VII of the Finance Act, 2013 (17 of 2013);
(5) “fees for technical services” shall have the meaning assigned to it in section 9(7)(b);
(6) “housing finance company” means a public company formed or registered in India with the main object of carrying on the business of providing long-term finance for construction or purchase of houses in India for residential purposes;
(7) “Indian Institute of Technology” shall have the same meaning as that of “Institute” defined in section 3(g) of the Institutes of Technology Act, 1961 (59 of 1961);
(8) “Keyman insurance policy” shall have the meaning assigned to it in Schedule II (Note 1);
(9) “limited liability partnership” shall have the same meaning as assigned to it in section 2(1)(n) of the Limited Liability Partnership Act, 2008 (6 of 2009);
(10) “long-term finance”, for the purposes of section 32(e), means any loan or advance where the terms under which moneys are loaned or advanced provide for repayment along with interest thereof during a period of not less than five years;
(11) “micro enterprise” shall be an enterprise classified as such under the notification in this behalf by the Central Government under the Micro, Small and Medium Enterprises Development Act, 2006 (27 of 2006);
(12) “mineral oil” includes petroleum and natural gas;
(13) “moneys payable” in respect of any tangible asset [as referred to in section 33(12)(a)(i)] includes— (a) any insurance, salvage or compensation moneys payable in respect thereof; (b) where the asset is sold, the price for which it is sold;
(14) “non-scheduled bank” means a banking company as defined in section 5(c) of the Banking Regulation Act, 1949 (10 of 1949), which is not a scheduled bank;
(15) “paid” means, except for section 37, actually paid or incurred according to the method of accounting upon the basis of which the profits or gains are computed under the head “Profits and gains of business or profession”;
(16) “permanent establishment” shall have the meaning assigned to it in section 173(c);
(17) “plant” includes ships, vehicles, books, scientific apparatus and surgical equipment used for the business or profession but does not include tea bushes or livestock or buildings or furniture and fittings;
(18) “predecessor entity” means— (a) the amalgamating Indian company in the case of amalgamation; (b) the demerged Indian company, in the case of demerger; (c) a firm, in the case of a succession of a firm by a company as referred to in section 70(1)(zd); (d) a private company or unlisted public company, in case of conversion as referred to in section 70(1)(ze);
(19) “primary agricultural credit society” shall have the same meaning as assigned to it in Part V of the Banking Regulation Act, 1949 (10 of 1949);
(20) “primary co-operative agricultural and rural development bank” means a society having its area of operation confined to a taluk and the principal object of which is to provide for long-term credit for agricultural and rural development activities;
(21) “professional services” shall have the meaning assigned to it in section 402(28);
(22) “public company” shall have the same meaning as assigned to it in section 2(71) of the Companies Act, 2013 (18 of 2013);
(23) “public financial institution” shall have the same meaning as assigned to it in section 2(72) of the Companies Act, 2013 (18 of 2013);
(24) “rate of exchange” means the rate of exchange determined or recognised by the Central Government for the conversion of Indian currency into foreign currency or foreign currency into Indian currency;
(25) “royalty” shall have the same meaning as assigned to it in section 9(6)(b);
(26) “rural branch” means a branch of a scheduled bank or a non-scheduled bank situated in a place which has a population of not more than ten thousand according to the last preceding census, of which the relevant figures have been published before the first day of the tax year;
(27) “scientific research” means— (a) any activity for the extension of knowledge in the fields of natural or applied science including agriculture, animal husbandry or fisheries; and (b) the references to expenditure incurred on scientific research shall include all expenditure incurred for the prosecution, or the provision of facilities for the prosecution, of scientific research, but does not include any expenditure incurred in the acquisition of rights in, or arising out of, scientific research, and the references to scientific research related to a business or class of business shall include any scientific research— (i) which may lead to or facilitate an extension of that business or, all businesses of that class; (ii) of a medical nature which has a special relation to the welfare of workers employed in that business or, all businesses of that class;
(28) “securities transaction tax” shall have the meaning assigned to it under Chapter VII of the Finance (No. 2) Act, 2004 (23 of 2004);
(29) “service”, for the purposes of section 26(2)(h), means a service of any description which is made available to potential users and includes the provision of services in connection with business of any industrial or commercial nature such as— (a) accounting; (b) banking; (c) communication; (d) conveying of news or information; (e) advertising; (f) entertainment;(g) amusement; (h) education; (i) financing; (j) insurance; (k) chit funds; (l) real estate; (m) construction; (n) transport; (o) storage; (p) processing; (q) supply of electrical or other energy; and (r) boarding and lodging;
(30) “small enterprise” shall be an enterprise classified as such under the notification in this behalf by the Central Government under the Micro, Small and Medium Enterprises Development Act, 2006 (27 of 2006);
(31) “speculative transaction” means a transaction in which a contract for the purchase or sale of any commodity, including stocks and shares, is periodically or ultimately settled otherwise than by the actual delivery or transfer of the commodity or scrips, other than the following transactions:— (a) a specified derivative transaction as defined in clause (33); (b) a contract in respect of raw materials or merchandise entered into by a person in the course of his manufacturing or merchandising business to guard against loss through future price fluctuations in respect of his contracts for actual delivery of goods manufactured, or merchandise sold by him; (c) a contract in respect of stocks and shares entered into by a dealer or investor therein to guard against loss in his holdings of stocks and shares through price fluctuations; (d) a contract entered into by a member of a forward market or a stock exchange in the course of any transaction in the nature of jobbing or arbitrage, to guard against loss which may arise in the ordinary course of his business as such member;
(32) “Specified Banking or Online Mode” shall mean transaction by an account payee cheque or an account payee bank draft or use of electronic clearing system through a bank account or through such other electronic mode, as may be prescribed;
(33) “specified derivative transaction” means any transaction in respect of trading in derivatives referred to in section 2(ac) of the Securities Contracts (Regulation) Act, 1956 (42 of 1956); or in respect of trading in commodity derivatives (other than agricultural commodity derivatives) which is chargeable to commodities transaction tax under Chapter VII of the Finance Act, 2013 (17 of 2013) or in respect of trading in agricultural commodity derivatives, if such transactions are— (a) is carried out— (i) through a stock broker or such other intermediary registered under section 12 of the Securities and Exchange Board of India Act, 1992 (15 of 1992) in accordance with the provisions of the Securities Contracts (Regulation) Act, 1956 (42 of 1956) or the Securities and Exchange Board of India Act, 1992 (15 of 1992) or the Depositories Act, 1996 (22 of 1996) and the rules, regulations or bye-laws made or directions issued under those Acts; or (ii) by banks or mutual funds, electronically on screen-based systems of a recognised stock exchange; and (b) supported by a time stamped contract note issued by the intermediary to every client indicating in the contract note— (i) the unique client identity number allotted under any law in force; and (ii) the Permanent Account Number allotted under this Act;
(34) “State Government undertaking” includes— (a) a corporation established by or under any State Act; (b) a company in which more than 50% of the paid-up equity share capital is held by the State Government; (c) a company in which more than 50% of the paid-up equity share capital is held by the entity referred to in clause (a) or (b) (whether singly or taken together); (d) a company or corporation in which the State Government has the right to appoint the majority of the directors or to control the management or policy decisions, directly or indirectly, including by virtue of its shareholding or management rights or shareholders agreements or voting agreements or in any other manner; (e) an authority, a board or an institution or a body established or constituted by or under any State Act, or owned or controlled by the State Government;
(35) “State Industrial Investment Corporation” means a Government company within the meaning of section 2(45) of the Companies Act, 2013 (18 of 2013), engaged in the business of providing long-term finance for industrial projects;
(36) “State Financial Corporation” means a Financial Corporation established under section 3 or 3A or an institution notified under section 46 of the State Financial Corporations Act, 1951 (63 of 1951);
(37) “successor entity” means— (a) the amalgamated Indian company, in the case of amalgamation; (b) the resulting Indian company, in the case of demerger; (c) a company, in case of a succession of a firm by a company as referred to in section 70(1)(zd); (d) a limited liability partnership, in case of conversion of private company or unlisted public company to a limited liability partnership, as referred to in section 70(1)(ze);
(38) “taxable commodities transaction” shall have the meaning assigned to it under Chapter VII of the Finance Act, 2013 (17 of 2013);
(39) “taxable securities transaction” shall have the meaning assigned to it under Chapter VII of the Finance Act, 2004 (13 of 2004);
(40) “University” shall have the meaning assigned to it in section 70(2) (Table: Sl. No. 7).
Introduction
Part D's business-computation terms have statutory meanings that can differ from an accounting or commercial use. Section 66 resolves, among others, payment timing, specified banking modes, related entities and professional-service expressions.
Key takeaways
Part D interpretation
The section defines business-computation terms such as paid, plant, scientific research, speculative transaction and specified banking or online mode.
Definition controls scope
A taxpayer should apply the defined meaning for the relevant deduction or presumptive rule instead of relying on an ordinary commercial label.
Selected definitions
Section 66 contains 40 definitions. Commonly relevant examples include:
- "Banking company" - a company to which the Banking Regulation Act, 1949 applies, including any bank or banking institution referred to in Section 51 of that Act.
- "Commission or brokerage" - has the meaning assigned in Section 402(7).
- "Fees for technical services" - has the meaning assigned in Section 9(7)(b).
- "Housing finance company" - a public company formed or registered in India mainly to provide long-term finance for construction or purchase of houses in India for residential purposes.
- "Long-term finance" (for Section 32(e)) - a loan or advance repayable, with interest, over a period of not less than five years.
- "Permanent establishment" - has the meaning assigned in Section 173(c).
- "Plant" - includes ships, vehicles, books, scientific apparatus and surgical equipment used for the business or profession, but excludes tea bushes, livestock, buildings, or furniture and fittings.
- "Royalty" - has the same meaning as assigned in Section 9(6)(b).
- "Scientific research" - activity for the extension of knowledge in natural or applied science (including agriculture, animal husbandry or fisheries), covering related expenditure but excluding expenditure to acquire rights in, or arising out of, scientific research.
- "Specified Banking or Online Mode" - transaction by account payee cheque, account payee bank draft, electronic clearing system through a bank account, or other prescribed electronic mode.
- "Speculative transaction" - a transaction where a contract for purchase/sale of a commodity (including stocks and shares) is settled otherwise than by actual delivery, with specific carve-outs for hedging contracts, dealer/investor hedging in stocks and shares, jobbing/arbitrage by exchange members, and specified derivative transactions.
- "Specified derivative transaction" — the categories include securities derivatives, non-agricultural commodity derivatives chargeable to commodities transaction tax, and agricultural commodity derivatives. Clause (33) also requires the specified intermediary/bank/mutual-fund route, electronic screen-based trading on a recognised stock exchange, and a time-stamped contract note identifying the client and PAN. These requirements are cumulative, not alternatives to recognised-exchange trading.
Other terms defined
Section 66 also defines: "agreement" (for Section 26(2)(h)), "commodities transaction tax" and "commodity derivative," "Indian Institute of Technology," "Keyman insurance policy," "limited liability partnership," "micro enterprise" and "small enterprise," "mineral oil," "moneys payable," "non-scheduled bank," "paid," "predecessor entity" and "successor entity" (for amalgamation/demerger/succession/conversion scenarios), "primary agricultural credit society," "primary co-operative agricultural and rural development bank," "professional services," "public company," "public financial institution," "rate of exchange," "rural branch," "securities transaction tax," "service" (for Section 26(2)(h)), "State Government undertaking," "State Industrial Investment Corporation," "State Financial Corporation," "taxable commodities transaction," "taxable securities transaction," and "University."
Definitions change the operative rule
Read 'paid' with its Section 37 exception before deciding the deduction year.
For a cash-payment restriction, use the defined specified banking or online modes rather than a general assumption that any electronic transfer qualifies.
Step-by-step flow for using Section 66 definitions
- 1
Is the term used in Part D of Chapter IV (business or profession)?
- No: Look for the definition applicable to that other part of the Act.
- Yes: Go to the next step.
- 2
Is the definition limited to a particular provision?
For example, "agreement" and "service" apply for Section 26(2)(h), "long-term finance" for Section 32(e), and "paid" applies except for Section 37.
- 3
Does it borrow a meaning from elsewhere?
For example, "royalty" (Section 9(6)(b)), "fees for technical services" (Section 9(7)(b)), "permanent establishment" (Section 173(c)), and terms from the Banking Regulation Act, 1949 or the Companies Act, 2013. Read that source.
- 4
Apply the inclusions and exclusions
For example, "plant" includes vehicles and books but not buildings, furniture, tea bushes or livestock. A "speculative transaction" excludes the listed hedging, jobbing or arbitrage, and specified derivative transactions.
- 5
Apply the operative section
The definition only sets the meaning. The deduction or charge comes from the section that uses the term.
Practical checklist
Do
- Link each technical phrase in a Part D claim to its Section 66 clause.
- Record why a taxpayer, payment or transaction meets a special definition before calculating the amount.
Avoid
- Do not carry an ordinary dictionary meaning into an expressly defined Part D term.
Illustrative example
Scenario: a spinning mill's contracts and assets
Hypothetical facts (illustration only, not a real taxpayer): Mr. Iyer runs a spinning mill that manufactures cotton yarn and has contracts to deliver yarn to buyers. To guard against loss from future price changes in raw cotton, he enters into a forward contract for raw cotton that is settled by paying the price difference, not by delivery. He also enters into share contracts that are settled without delivery and are not hedges of any shareholding. He buys a delivery van and new office furniture.
Raw-cotton forward contract
It is settled otherwise than by actual delivery. However, clause (31)(b) excludes "a contract in respect of raw materials or merchandise entered into by a person in the course of his manufacturing or merchandising business to guard against loss through future price fluctuations in respect of his contracts for actual delivery of goods manufactured, or merchandise sold by him". Raw cotton is a raw material of his yarn manufacturing business, and the contract guards against loss on his contracts for actual delivery of the yarn he manufactures. So it is not a "speculative transaction".
Share contracts
They are settled otherwise than by delivery. They are not hedges by a dealer or investor, and nothing in the facts shows they are specified derivative transactions under clause (33). They fall within "speculative transaction".
Delivery van
Vehicles used for the business are expressly included in "plant" under clause (17).
Office furniture
Furniture and fittings are expressly excluded from "plant", so they are not "plant" under this definition. Their treatment depends on the operative depreciation provision.
Outcome
- The same person can have both speculative and non-speculative contracts. The definition decides each one separately.
- Classification under Section 66 feeds into the operative sections. It does not by itself give or deny a deduction.
Glossary
- Part D
- The Chapter IV part governing profits and gains of business or profession.
- Specified banking or online mode
- Payment channels defined for the Act's business-computation rules.
Frequently asked questions
What is Section 66 for?
It is a definitions/interpretation section supplying the meaning of technical terms - like "banking company," "plant," "royalty," "permanent establishment" and "speculative transaction" - used throughout Part D of Chapter IV of the Income-tax Act, 2025.
Does "plant" include buildings or livestock under this Act?
No - Section 66(17) specifically excludes tea bushes, livestock, buildings, and furniture and fittings from the definition of "plant," while including ships, vehicles, books, scientific apparatus and surgical equipment used for the business or profession.
Need help applying this provision to your situation?
Talk to our tax team about how these definitions apply to youLast updated 10 October 2026