Selling your Mumbai flat to buy bigger in Navi Mumbai: tax and timing

Do we sell our flat first, or buy the new one first? You own a small flat in Mumbai and want a bigger one across the creek. That question sits under all the others.

Picture a couple in their late thirties with a seven-year-old. They own a 1 BHK in Chembur, bought thirteen years ago. Their child still sleeps in their room. A 2 or 3 BHK in Kharghar or Nerul looks possible if they sell. They’re an illustration, not a real family.

Their friends disagree. One says, “Buy under construction and save all the tax.” Another says, “Never sell before you buy.” Both are half right. The plain version: the tax on your profit can fall away if it goes into the new home on time. The real risk is timing, so let’s work through it calmly.

Your profit is taxed at 12.5%, unless it goes into the new home

The tax falls on your profit, not on the whole sale price. Own the flat for more than 24 months, and that profit counts as long-term. Our couple are past that.

On a long-term profit, the rate is 12.5%, with no adjustment for inflation.

There’s an older option too. If you’re a resident and bought before 23 July 2024, you may instead raise your purchase cost for inflation and pay 20% on the smaller profit. You pay whichever is lower. Your CA (chartered accountant) works out both.

Then the relief. Most people know it as section 54; the new tax law of 2025 renumbers it section 82. Put the profit into one new home within the time limits, and that profit isn’t taxed, up to a cap of ₹10 crore. Confirm your own case with your CA.

Three windows start on the day you sell

Every deadline counts from the date you sell the old flat. You can buy a home up to 1 year before the sale or 2 years after it, or build one within 3 years. Does booking a flat being built count? See the next section, and confirm with your CA. Say our couple sell in January 2027:

1. January 2026 The earliest a purchase counts: one year before the sale.
2. January 2027 The example sale. Every clock starts here.
3. Before you file that year’s return Any profit not yet spent on the new home goes into the Capital Gains Account Scheme, by the return’s due date.
4. January 2029 The last month to buy a ready home: two years after.
5. January 2030 The last month for a home being built to be finished: three years after.

What’s the account scheme? It’s a special bank deposit that holds the unspent profit until you buy. Whatever’s still unspent when the period ends is taxed as a gain that year.

Tribunals have treated an under-construction flat as building, but it’s contested

Several tax tribunal benches have treated booking with a builder as building a home. That gives you 3 years, not 2. Tribunals don’t all agree, and we found no High Court ruling on it.

In a 2017 case, the Mumbai bench of the tax tribunal held that buying a flat being built is construction, not purchase. Another Mumbai bench relied on two 1986 and 1993 circulars of the CBDT, the board that runs income tax.

In that second case, the department opposed the claim, arguing the flat wasn’t finished within 3 years. The tribunal said a buyer shouldn’t be blamed for the builder’s late handover.

So check the handover month against your window. Possession means the handover of keys. MahaRERA (the state’s register of approved projects) shows the builder’s month. For our couple’s January 2027 sale:

• Millennium Celesta, Kharghar: ₹96 lakh to ₹1.38 crore, possession May 2029. About eight months of room.
• Gami Avant, Vashi: ₹1.34 crore to ₹2.29 crore, possession Dec 2029. One month of room.
• Neel Amplus, Kharghar: ₹71 lakh to ₹96 lakh, possession Dec 2030. That’s after the window ends.

Now the honest downside. If only the 2-year purchase window applied, the deadline would be January 2029. None of these three would make it. Put that question to your CA before you book.

Handover dates can slip, and MahaRERA can extend a project’s registration. In August 2026 it ordered an automatic four-month extension. It covers projects whose completion dates fall on or after 28 February 2026.

Projects registered from 1 August 2026 aren’t included. With one month of room, even a short slip takes the Vashi flat past the window.

So leave a margin, and read each project’s own MahaRERA page. Our guide to your rights when possession runs late explains your options.

A worked example: what our Chembur couple might pay

These are round example figures, not a valuation. Say they paid ₹40 lakh in 2012-13 and sell for ₹1.2 crore.

Their cost is raised in line with the tax department’s inflation index, which went from 200 to 384. That nearly doubles it, to ₹76.8 lakh.

The relief is the lower of two things: your profit, or what the new flat costs. Say they buy at ₹1.5 crore. The profit is the lower one, so all of it is covered.

One catch: sell the new flat within three years of buying it, and the profit you saved tax on is added back. Under section 82, the profit you didn’t pay tax on is taxed then. Staying three years or more while your child settles in? Then it won’t touch you.

And the money gap? The new flat plus 7% stamp duty (the state’s tax on buying a home) needs about ₹1.6 crore.

Against their sale, that leaves roughly ₹40 lakh to borrow. That’s before brokerage, registration and moving, and it assumes the old home loan is paid off. Whatever they still owe comes off the sale money first, so ask your bank for the payoff figure.

Sell first or buy first: each way costs you something

Selling first is safer for your money; buying first is easier on your family. Buying first can mean two EMIs (monthly loan payments) at once. Could you carry both for a year?

	Sell first	Buy first
What you pay	Rent, and two moves	Two EMIs, or a bridge loan
The tax	Profit waits in the account scheme	Buying up to a year early still counts
The risk	Nothing fits in time	The old flat sells slowly, or for less
Who it suits	Families who’d strain on two EMIs	Families who can carry both loans

For our couple, selling first means renting near the child’s school for a while. What’s a bridge loan? It’s a short-term secured loan to cover the gap between buying and selling, as one lender puts it. Ask your bank whether it offers one, and on what terms.

RBI’s July 2025 rules bar prepayment charges on floating-rate loans to individuals, but only for loans sanctioned or renewed from 1 January 2026. A loan from 2013 isn’t covered by that date. Read your loan agreement, and ask the bank in writing what closing it early will cost.

Selling has its own costs, and the buyer keeps back 1%

Three costs come off your sale price.

• Brokerage. There’s no fixed legal rate; brokers usually charge each side. Agree it in writing.
• Society transfer fee. The Bombay High Court has noted a ceiling of ₹25,000 for a society’s transfer fee. Who pays it depends on your society’s practice.
• TDS (tax deducted at source). On a sale of ₹50 lakh or more, your buyer keeps back 1% and files it with the tax department. You claim it back in your return; confirm with your CA.

On our couple’s sale, that 1% is ₹1.2 lakh they’ll see later, not on the day. Our resale flat documents guide shows the papers in order.

Buying resale in Navi Mumbai instead? Many Navi Mumbai flats stand on leasehold land from CIDCO (the state company that planned Navi Mumbai). For 2026-27, its transfer charge on a 61 to 70 sq m flat in a developed node is ₹2,58,400. Our CIDCO leasehold guide explains it.

Your flat’s value sets the whole plan

Everything above hangs on one number: what your flat will really sell for.

Portals show what sellers ask, not what flats register at. One puts Chembur near ₹32,650 per sq ft (the price of each square foot of floor), on asking prices from May 2026. Yours may differ a lot.

The Harbour line you know from Chembur runs on through Vashi and Nerul. Ride it once at office time before you book.

Kharghar1.02 crore

Nerul1.89 crore

Seawoods2.25 crore

Vashi3.2 crore

These are starting prices, often for the smallest flat. For our couple’s 2 or 3 BHK, Kharghar has the most choice, while Nerul costs more.

The simple rule: get your flat valued first. Pick a new home whose MahaRERA date sits well inside three years of your sale, and ask your CA what happens if only two years apply. Sell first, unless you can pay two EMIs for a year without strain. Confirm the tax with your CA before you sign either deal.

Who should wait? If you’ve owned your flat for two years or less, there’s no relief yet. If a mid-year school move would be hard on your child, time the sale around it.

Start with what your flat is worth

Your sale price decides the loan, the tax and the order. So ask for the home valuation on this page. The advisor named there will help you put a fair number on your flat. Then let’s lay your dates beside the new flat’s MahaRERA month.

Questions buyers ask

Do I have to put the whole sale price into the new home?

No. The relief covers the profit, up to what the new home costs. Your CA can confirm the split.

Can I buy two flats with the profit?

Only once in your life, and only if the profit is ₹2 crore or less. Your CA can confirm if you qualify.

What if I haven’t bought by the time I file my return?

Put the unspent profit into the Capital Gains Account Scheme before you file, by the due date. Your CA can open it with you.

How we checked: possession months and prices are from our MahaRERA-checked project records, read 7 November 2026. Tax points are from the dated sources listed. The example sums are our own arithmetic.