The bedrock is the Indian Contract Act 1872. Section 10 of the Act makes an agreement a contract only when it is made by the free consent of parties competent to contract, for a lawful consideration and with a lawful object. A consultancy agreement therefore needs a clear offer and acceptance, a fee that counts as real consideration, and parties of sound mind and majority age under Section 11. Free consent under Sections 13 to 19 means the agreement must be free of coercion, undue influence, fraud or misrepresentation, or it becomes voidable at the option of the wronged party.
One clause deserves particular care. Section 27 of the Act voids any agreement that restrains a person from carrying on a lawful profession, trade or business. This is why a broadly drafted post-termination non-compete on a consultant rarely holds up in an Indian court, even though a reasonable confidentiality and non-solicitation clause usually does. Restraints that bite only during the term of the engagement are treated more generously than those that try to bind the consultant after the relationship ends.
Tax and compliance sit alongside the contract law. A client paying a consultant for professional services deducts TDS at 10 percent under Section 194J of the Income Tax Act 1961, and a consultant whose turnover crosses the threshold must register under the Central Goods and Services Tax Act 2017 and charge GST. Electronic signature is fully valid here: the Information Technology Act 2000 recognises contracts signed online, so a consultancy agreement executed by e-signature is enforceable. For the authoritative text of the governing statute, the India Code official publication of the Indian Contract Act 1872 is the source to rely on. Stamp duty still applies under the Indian Stamp Act 1899 and the relevant State law, and an unstamped or under-stamped agreement can be refused as evidence in court until the duty and penalty are paid.