Will law itself is central, but the practice around registration, probate and stamp duty shifts by State, and those differences decide how smoothly an estate settles.
Maharashtra makes the distinction sharpest because probate is effectively unavoidable for many estates. Under the Indian Succession Act, probate of a will is mandatory where the will is made by a Hindu, Buddhist, Sikh or Jain within the ordinary original civil jurisdiction of the Bombay High Court, or relates to immovable property situated there. Testators in Mumbai routinely register the will with the Sub-Registrar to ease that later probate, and the Maharashtra registration fee for a will is modest and fixed rather than ad valorem.
West Bengal sits under the same probate rule for the territory of the Calcutta High Court's original jurisdiction, so a Kolkata testator should expect probate to be required for Hindu wills there. The state's registration offices are well used to depositing wills in sealed cover under Section 42 of the Registration Act, an option that adds secrecy on top of authenticity.
Tamil Nadu, covering the Madras High Court's original jurisdiction, completes the trio of presidency towns where probate of Hindu wills is compulsory. Outside these original-side jurisdictions, across most of Karnataka, Delhi, Uttar Pradesh and the rest of the country, probate is generally optional and an executor can act on the will directly, though banks and registrars often ask for it before transferring high-value assets.
Across every State the constants hold: no stamp duty on the will, registration optional under Section 18, and the two-witness rule of Section 63 non-negotiable. What changes is only how strongly local institutions push for registration or probate before they release assets, and in the four presidency-jurisdiction cities that push is strongest.