Undivided share of land (UDS)

Buy a flat and you do not just buy the flat. You also buy a slice of the land it stands on – the plot, the driveway, the lobby, the lift shaft, the compound wall – shared with every other owner in the building. That slice is your undivided share of land, UDS for short. It never becomes a fenced-off plot with your name on it; it stays undivided, mixed in with everyone else’s, for as long as the building stands.

Most buyers notice UDS only as a line in the sale deed, if they notice it at all. That is a mistake. UDS decides what you actually own beneath the flat, what you are paid if the land is ever acquired, how much your vote in the owners’ association is worth, and what happens to your stake if the building is one day pulled down and rebuilt. This guide works through where UDS appears in your paperwork, how it is meant to be calculated, a worked example you can follow with a calculator, and the red flags worth checking before you sign.

What UDS is

A multi-storey building sits on one piece of land, but the flats on it are sold to dozens or hundreds of separate owners. Indian law has no concept of owning a floor in mid-air without also owning some share of the ground beneath it, so every apartment sale carries two things bundled together: the flat itself, and a fractional, undivided interest in the land and every part of the building that is not inside anyone’s flat – the common areas. The Karnataka Apartment Ownership Act, 1972 (KAOA), which governs most apartment buildings in the state, defines an apartment owner as someone owning both: “the person or persons owning an apartment and an undivided interest in the common areas and facilities in the percentage specified and established in the Declaration.”

“Undivided” is the operative word. You do not own a specific, walkable patch of the compound; you own a fraction of the whole plot, held jointly with every other flat owner, in the same way three people who buy one painting together might each own a third of it rather than a third of the canvas. KAOA makes this explicit for the building’s shared spaces: “The common areas and facilities shall remain undivided and no apartment owner or any other person shall bring any action for partition or division of any part thereof,” unless the whole property is formally taken out of the Act – which the later sections of this guide come back to.

Where UDS appears

UDS is not a separate document. It is a figure that has to show up, correctly, inside three papers you already handle when you buy a flat.

In the agreement for sale

Karnataka’s model agreement for sale gives the allottee “undivided proportionate share in the Common Areas,” and spells out why it cannot be carved off: “Since the share / interest of Allottee in the Common Areas is undivided and cannot be divided or separated, the Allottee shall use the Common Areas along with other occupants, maintenance staff etc., without causing any inconvenience or hindrance to them.” At this stage the share is usually described only in general terms; our agreement-for-sale guide walks through the rest of what the model form covers.

In the deed of declaration

Once a building is brought under KAOA, a deed of declaration is registered for it. This is where your exact percentage is fixed, flat by flat, and it is meant to state “the value of the property and of each apartment, and the percentage of undivided interest in the common areas and facilities appurtaining to each apartment and its owner for all purposes, including voting.” Every flat in the building should have an entry here, and the percentages are what everything else in this guide is built on.

In the sale deed

The sale deed is what actually transfers ownership to you, and its schedule should restate the UDS as a concrete figure – typically so many square feet of undivided share out of the site’s total extent, alongside your flat number and carpet area. Even if it does not, KAOA says the share follows the flat anyway: it “shall not be separated from the apartment to which it appertains, and shall be deemed to be conveyed or encumbered with the apartment even though such interest is not expressly mentioned in the conveyance or other instrument.” That is a safety net, not a reason to skip checking the figure yourself – see the red flags below.

RERA adds its own version of the same requirement for how a promoter finishes the job. The conveyance the promoter must eventually register is not just for the flat: “The promoter shall execute a registered conveyance deed in favour of the allottee along with the undivided proportionate title in the common areas to the association of the allottees or the competent authority, as the case may be,” and hand over the common areas to the association at the same time.

How the share is worked out

KAOA is specific about the basis for the calculation, and it is not floor area. “Each apartment owner shall be entitled to an undivided interest in the common areas and facilities in the percentage expressed in the Declaration. Such percentage shall be computed by taking as a basis the value of the apartment in relation to the value of the property.” The declaration is meant to record both figures side by side: the value of the whole property, and the value of each apartment.

Value, not carpet area and not built-up area, is the legal test. In practice the two often move together, because flats in one project are usually priced within a narrow band per square foot, so a bigger flat tends to carry both a higher value and a bigger share – which is why builders and buyers alike commonly talk about UDS as if it were simply proportional to size. That shorthand is close enough for most same-project comparisons, but it is only an approximation of the actual legal basis, and it can break down where floors, views or fittings are priced very differently within the same building. The declaration, not a size-based guess, is what actually governs. Once fixed, the percentage cannot be moved: “The percentage of the undivided interest of each apartment owner in the common areas and facilities as expressed in the Declaration shall have permanent character, and shall not be altered without the consent of all of the apartment owners expressed in an amended Declaration duly executed and registered.”

Why your share matters

UDS is not paperwork trivia. It decides four separate things, each with its own consequence if you get the figure wrong or never check it.

Redevelopment and rebuilding

KAOA, the Act that governs most existing apartment buildings, was written in 1972 and has no chapter on redevelopment as such. A new Karnataka apartment law passed the state legislature in August 2026, but it was not yet in force as of 10 Sep 2026, so the 1972 Act is still what applies. Under it, the closest thing to a redevelopment route is section 14: all the owners together can take the property out of the Act by a registered instrument, at which point “the property shall be deemed to be owned in common by the apartment owners,” each holding exactly the percentage they held as UDS beforehand. Section 22 covers the other route into common ownership: if the building is damaged or destroyed and the association does not decide to repair or rebuild within 60 days, the same thing happens automatically, and if the property is then sold, “the net proceeds of sale together with the net proceeds of the insurance on the property, if any... shall be divided among all the apartment owners in percentage equal to the percentage of undivided interest owned by each owner.” Either way, your UDS percentage is the number that decides your share of whatever comes next.

If the land is acquired

Government bodies do sometimes acquire land under an existing building – for road widening or a metro alignment, for instance – under the Right to Fair Compensation and Transparency in Land Acquisition, Rehabilitation and Resettlement Act, 2013. Compensation is paid to everyone with an interest in the land, and where there is a dispute about how to split it, the law sends that dispute up the chain rather than assuming an equal split: “When the amount of compensation has been settled, if any dispute arises as to the apportionment of the same or any part thereof, or as to the persons to whom the same or any part thereof is payable, the Collector may refer such disputes to the Authority.” A clearly documented UDS percentage, matching your declaration and sale deed, is your evidence of what you are entitled to if that ever happens.

Resale

Your flat and its UDS travel together at resale, by the same instrument: KAOA treats an apartment plus its percentage as one piece of “heritable and transferable immovable property,” transferable “by way of sale, mortgage, lease, gift, exchange or in any other manner whatsoever” in the same way as any other property. A buyer’s lawyer, and a lender valuing the flat for a loan, will both check that the UDS in your sale deed matches the declaration. A share that looks too small, too large, or simply absent is exactly the kind of mismatch that slows down – or kills – a resale.

Your vote in the association

KAOA weights voting by UDS, not by a flat-one-vote rule. “Majority” is defined as “the apartment owners with fifty-one per cent or more of the votes in accordance with the percentages assigned in the Declaration to the apartments for voting purposes,” and the declaration is required to record each flat’s percentage “for all purposes, including voting.” An owner with a larger UDS carries more weight in a vote to change the bye-laws, approve a big repair, or remove the property from the Act under section 14. The same percentage also sets your share of common expenses under section 10, which our maintenance guide covers in full.

A worked example

Take a hypothetical 120-flat project on a 2-acre plot – illustrative figures only, not a real project. Two acres works out to 87,120 sq ft (43,560 sq ft to the acre). Assume the 120 flats add up to 1,44,000 sq ft of built-up area between them – an average of 1,200 sq ft, a plausible mix of 2, 3 and 4 BHK units. A 1,300 sq ft flat in this project, using floor area as a stand-in for value as explained above, works out to:

1,300 ÷ 1,44,000 × 87,120 = 786.5 sq ft of UDS, or about 0.9% of the plot.

Keep the method in mind rather than the exact numbers: your share of the total built-up area, applied to the total plot. What actually governs your flat is the percentage printed in its declaration, not a recalculation you do yourself – but doing the arithmetic once is the fastest way to see whether a declaration’s numbers look roughly right.

Red flags to check

A handful of problems account for most UDS disputes, and all of them are things you can check before you sign rather than after.

• No UDS figure anywhere in the sale deed. The law deems the share conveyed with the flat even if the deed is silent, under KAOA section 6(2) – but a deed that never states the figure gives you nothing to point to later, and makes a future resale harder to finance. Insist on seeing it in writing.
• The sale deed figure does not match the declaration. These should be the same number. A mismatch is either a drafting error or a sign the declaration was never updated after the building changed.
• Similar flats, very different percentages, with no explanation. Since the legal basis is value, a floor premium or a corner unit can justify a difference – but a difference with no apparent reason is worth asking the builder or the association to explain.
• No deed of declaration at all. If the building has never been formally brought under KAOA, there is no registered document fixing anyone’s percentage, which weakens every buyer’s position, not just yours.
• A declaration nobody has updated after a change. Because the percentage “shall not be altered without the consent of all of the apartment owners,” any addition to the building – an extra floor, a converted terrace – that was never reflected in an amended, registered declaration leaves the numbers on paper out of step with the building on the ground.

The land-plus-construction split

One arrangement sometimes offered as a way to cut stamp duty is to split a flat’s purchase into two documents: a sale deed for the undivided share of land alone, plus a separate construction agreement for the building. The idea is that duty on the land-only deed, valued at the bare land rate, comes to less than duty on a completed flat. Karnataka’s stamp law closes this off directly. The article covering a promoter’s or developer’s conveyance of a flat or apartment defines what is being sold to include the UDS itself – “'Premises' means and includes undivided interest in the land, building and proportionate share in the common areas” – and charges duty accordingly: “the same duty as a conveyance... on the market value equal to the market value of the fully constructed flat or apartment or unit, irrespective of the stage of construction, deeming it as fully constructed.”

A Comptroller and Auditor General audit of Karnataka’s stamp department found parties trying exactly this split in practice, and traced what happened to it: buyers had “entered into a Sale Agreement for sale of undivided share of land with the land Owner and a Construction Agreement with the Developer,” and argued they were “obtaining the constructed area by virtue of getting ownership of undivided share of land.” The audit’s conclusion was blunt: “ownership of either the land or the built-up area cannot be transferred merely by an Agreement and title to a property can be transferred only through a proper conveyance,” so “whenever a sale takes place after construction of any apartment complex, Stamp Duty invariably would have to be levied on the built-up area, irrespective of the buyer.” In the cases it reviewed, the district registrar had already refused to accept the land-only valuation and assessed duty on the completed flat instead.

Our full-cost guide covers the rest of what stamp duty and registration add to a Bangalore flat.

Before you sign

• Ask for the UDS figure in writing before you pay a booking amount, not after.
• Check the deed of declaration for your flat’s exact percentage, and that the building has one at all.
• Match the sale deed’s figure to the declaration, square foot for square foot.
• Ask why, if two similar flats carry very different percentages, rather than assuming it is a typo or ignoring it.
• Remember the share is permanent: it cannot be changed later without every owner’s consent.
• Do not expect a UDS-plus-construction-agreement split to save stamp duty; Karnataka’s stamp law values the deed as a completed flat either way.