Combining Two Flats Into One: Section 54 Treatment

"Can I buy the two flats next to each other and still get one exemption?"

You've sold a large property and have a sizeable capital gain to reinvest. In your target high-rise — a common story in towers across Mumbai and Bengaluru — the family that owns the flat next to the one you like is also selling. Buy both, knock through a connecting wall, and you get a genuinely larger home than either flat alone could offer. It sounds like the perfect upgrade. Then the question surfaces: Section 54 of the Income Tax Act talks about reinvesting in "one residential house" — does buying two flats, even if you merge them, still qualify for the exemption on both, or does the tax department treat the second flat as a separate, non-exempt purchase?

This is a genuinely fact-specific area of tax law, shaped by years of tribunal and court decisions rather than one clean, black-letter rule. This article lays out the current position as it's generally understood, what facts have historically mattered, and — because this really is a "confirm before you commit" situation — where a chartered accountant or tax counsel needs to sign off before you finalise the purchase.

Context: "one residential house" and the merged-units position

The Income Tax Department's official Section 54 guidance provides exemption for the capital gain from selling a long-term residential house, when the gain is reinvested in "one residential house" in India. On a literal reading, this appears to limit the exemption to a single unit. However, over a series of tribunal and High Court decisions across different fact patterns, the position that has developed is that two (or more) physically adjacent or contiguous flats, which are combined and used as a single dwelling unit, can — on the specific facts — be treated as "one residential house" for the purpose of this exemption.

This is not a blanket rule that any two flats you buy automatically qualify. It is a fact-specific determination: the tax authorities and courts look at whether the units are genuinely functioning as one home — common access, a single kitchen, one electricity/water connection where feasible, and structural evidence of merger — rather than two independently usable flats that merely happen to be adjacent.

According to Tax2win's guide to Section 54, the exemption's "one residential house" condition has been interpreted flexibly in several judicial rulings where adjoining units were structurally converted into a single residence, but this remains an area where outcomes depend heavily on the specific documentation and facts presented — it is not a guaranteed entitlement simply because two flats happen to share a wall.

Step-by-step: structuring the purchase and evidencing a single dwelling

If you're planning this route, the sequence that best supports a "single house" position looks like this:

1. Identify genuinely adjacent or contiguous units — same floor with a shared wall, or vertically stacked with an internal staircase connection. Non-adjacent flats in the same building are a much weaker case.
2. Plan the structural merger before or immediately after purchase — get architectural drawings showing the combined layout, ideally prepared before you finalise the purchase so intent is documented from the start.
3. Obtain society and, where applicable, municipal/RERA approval for the merger — knocking through a shared wall in a high-rise typically requires society permission and, depending on the extent of structural change, municipal sanction.
4. Consolidate services where feasible — a single kitchen, shared common access, and (where the housing society and utility providers permit) combined electricity/water connections all strengthen the "single dwelling" evidence.
5. Retain all documentation: the architect's merger plan, society's no-objection/approval letter, any municipal sanction, and photographs of the completed merged layout.
6. Time both purchases within the Section 54 reinvestment window — 2 years from the sale to purchase, or 3 years to construct — and keep the combined reinvestment within the ₹10 crore cap that applies to Section 54/54F claims.
7. Have your CA or tax counsel review the fact pattern before you file, since this exemption is more likely to attract scrutiny than a standard single-flat purchase.

Use DrawMagic's financial planning suite to plan how your total gain splits across the two flats and stays within the ₹10 crore reinvestment cap, and DrawMagic's floor plan tool to actually draft and visualise the merged layout that will form part of your documentary evidence.

Merged single-house route vs. the separate two-house option

It's worth being clear that "combine two flats as one house" is a different, and separate, planning route from the once-in-a-lifetime option (introduced from AY 2020-21) that allows an individual to invest long-term capital gains in two separate residential houses, provided the capital gain does not exceed ₹2 crore, and this option can be used only once in the taxpayer's lifetime. Don't conflate the two:

Geographic and demographic specifics for this scenario

• High-rise reality: Combining two flats — either side-by-side on the same floor or one above the other with an internal connection — is a well-established practice in dense metro towers in Mumbai, Bengaluru, and similar high-rise-heavy markets, where family space needs often outgrow a single unit faster than the market offers larger single units at a comparable price point.
• Society and RERA considerations: Any structural merger inside a registered housing society typically needs the managing committee's approval, and significant structural changes (breaking load-bearing walls, altering the building's sanctioned plan) may also require municipal or RERA-linked sanction, depending on the extent of the work and local building bye-laws.
• The ₹10 crore cap: Section 54 (and the parallel Section 54F) reinvestment claims are capped at ₹10 crore in aggregate — a detail that matters more for premium combined-flat purchases in expensive metro towers than for smaller transactions.
• Confirm locally, always: Because this is a fact-specific, litigated area rather than a bright-line statutory rule, always confirm your specific plan with a CA or tax counsel familiar with recent rulings before committing funds — outcomes here genuinely turn on your documentation and facts, not a generic checklist.

Mini scenario: merging two 2BHKs into a 4BHK (illustrative)

Consider Aditi and Rohan, who sold their independent house in Chennai for a substantial gain and want to reinvest in a high-rise in the same city where their children's school is located. Two adjoining 2BHK flats on the same floor, together forming what would effectively be a 4BHK, come up for sale at the same time. Before finalising the purchase, they commission architectural drawings showing the merged layout — a single entry, one combined living area, and one kitchen — and confirm with the housing society that the internal wall between the units can be removed with committee approval.

They complete both purchases within the Section 54 window, obtain society approval and complete the structural merger within a few months, and retain the architect's plans, the society's approval letter, and post-merger photographs as their documentary file. Their CA reviews the fact pattern — genuine adjacency, documented merger, single functional dwelling — and advises that it supports a "one residential house" claim for the full reinvestment, subject to it being confirmed at assessment. This is presented as an illustrative scenario reflecting a commonly cited fact pattern, not a guarantee of outcome for every combined-flat purchase.

Documentation that supports the "one house" claim

• Architect-certified merger plans showing the combined layout as a single residential unit, ideally dated close to the purchase.
• Housing society approval or no-objection letter for structural changes connecting the units.
• Municipal or RERA sanction, where the extent of structural change requires it under local bye-laws.
• Evidence of consolidated use — a single kitchen, one main entrance, shared common areas — rather than two flats that remain independently lockable and usable.
• Utility consolidation, where feasible — combined or linked electricity/water connections can further support single-dwelling use, though this isn't always practically achievable in every building.
• Photographs of the completed merged layout, taken after the structural work is done, as ongoing evidence for assessment purposes.

Pro tips

• Get the merger plan drawn up before or immediately after purchase, not years later — a merger that happens well after the acquisition weakens the documentary link to the original claim.
• Involve your CA or tax counsel at the planning stage, not after you've already registered both purchases — this is an area where advance structuring genuinely matters.
• Don't assume every "adjacent" pair of flats qualifies — non-contiguous units in the same building, or units on different wings, are a materially weaker case.
• Track the ₹10 crore aggregate reinvestment cap carefully if you're combining two premium units in an expensive metro tower.
• Keep the separate two-house option in mind as an alternative if your gain is under ₹2 crore and physical merger isn't practical — it may be the simpler, less contested route.

Common mistakes to avoid

• Treating non-adjacent flats as one house — buying two flats in different parts of the same building without physical contiguity is a much harder position to sustain.
• No merger evidence at all — buying two flats and simply using them "as a family" without structural merger, society approval, or architectural documentation leaves the claim vulnerable.
• Assuming this route is risk-free — because it rests on judicial interpretation rather than explicit statutory text, it carries more scrutiny risk than a standard single-flat Section 54 claim.
• Confusing this with the separate two-house option — the two routes have different eligibility conditions (notably the ₹2 crore gain ceiling on the statutory two-house option) and shouldn't be mixed up when planning.
• Delaying the structural merger indefinitely — an unmerged pair of flats, purchased with the stated intent to combine "eventually," is a weaker fact pattern than a promptly executed and documented merger.

How DrawMagic fits into this plan

Planning a two-flat combination touches both the financial and the design side of your move. DrawMagic's financial planning workspace helps you model how your total capital gain splits across two purchase prices and stays within the ₹10 crore reinvestment cap, so you go into negotiations with clear numbers. DrawMagic's AI floor plan generator lets you actually draft the proposed merged layout — a genuinely useful exercise both for your own planning and as part of the documentary trail that supports a "single dwelling" position. And when you're searching for adjacent or contiguous units in your target building or locality, DrawMagic's property discovery tools help you shortlist and compare options against your reinvestment plan.

A value note

This is a fact-specific, litigated area of tax law, and the position described here reflects the general judicial trend as summarised by tax practitioners — it is not a guarantee of how any specific case will be assessed. DrawMagic is an information and software platform, not a broker, tax advisor, or legal counsel, and does not certify or guarantee any tax outcome. Before committing to a two-flat purchase on this basis, confirm your specific fact pattern with a chartered accountant and, given the litigation history in this area, ideally tax counsel as well.

Key takeaways

• Section 54 requires reinvestment in "one residential house," but adjacent/contiguous flats that are genuinely merged into a single dwelling have, on the facts, been treated as one house in various tribunal and court rulings.
• This is a fact-specific position, not a guaranteed entitlement — documentation of genuine physical and functional merger matters enormously.
• Key evidence includes architect-certified merger plans, society approval for structural changes, consolidated use (single kitchen, one entrance), and post-merger photographs.
• Don't confuse this route with the separate statutory two-house option, which has its own ₹2 crore gain ceiling and once-in-a-lifetime restriction.
• The overall Section 54/54F reinvestment cap of ₹10 crore applies to combined-flat purchases, which matters for premium metro properties.
• Structural changes to merge units typically require housing society approval, and possibly municipal/RERA sanction depending on scope.
• Plan and execute the merger promptly, and involve a CA or tax counsel before finalising the purchase, not after.
• Non-adjacent flats, or flats without documented merger evidence, present a materially weaker position for this exemption route.

FAQ

Can I just buy any two flats in the same building and claim Section 54 on both? No — the position that treats two units as "one residential house" applies specifically to genuinely adjacent or contiguous flats that are structurally and functionally merged into a single dwelling, evidenced by documentation. Non-adjacent flats without merger evidence are a much weaker case.

Is this the same as the "two separate houses" option under Section 54? No. The statutory two-house option (available once in a lifetime, only where the capital gain doesn't exceed ₹2 crore) doesn't require the houses to be adjacent or merged. The merged-flats position discussed here is a separate, judicially developed interpretation of "one residential house" and has no such statutory gain ceiling, but it does require genuine physical merger evidence.

Do I need society approval to merge two flats? Typically yes, for structural changes like removing a shared wall — housing societies generally require committee approval, and depending on the extent of the work, municipal or RERA-linked sanction may also be required under local bye-laws.

Planning a combined-flat purchase? Model your reinvestment in DrawMagic's financial planning suite, sketch the merged layout with the floor plan generator, and see what DrawMagic offers home buyers navigating complex upgrade moves.