A friend of mine spent almost four months “finalising” a flat in Mumbai. Not because she couldn't decide what she liked, but because every time she got close, something new came up that she hadn't thought to check. A RERA date that didn't add up. A maintenance clause nobody had explained properly. A stamp duty bill bigger than she'd budgeted for.
That's how it goes for most people buying a new flat in Mumbai. The market moves fast, brochures look polished, and sales teams are good at their jobs. But the things that actually decide whether you're happy with your choice a year later rarely show up on the glossy PDF they hand you at the site office.
Here's a more honest list. Not the textbook version, but what actually trips buyers up.
Don't Skip the RERA Check, Even If the Project Looks Established
Every residential project in Maharashtra is supposed to carry a RERA registration number, sitting right there on the brochure or hoarding. Most buyers glance at it and move on. Don't take five minutes, go to the MahaRERA website, and actually look the project up.
You're checking three things mainly: whether the promised possession date has already slipped (a lot of projects quietly get extended), whether the land title is clean, and whether the layout being marketed to you matches what's officially sanctioned. If a builder gets cagey when you bring up RERA, or claims the number is “still being processed,” that's not a small red flag. Walk away.
The Price on the Brochure Isn't the Price You'll Pay
This is probably the biggest gap between what buyers expect and what actually happens at the registration desk. The flat's quoted price is just the starting point. On top of that comes stamp duty (6% for male buyers, 5% for female buyers, since Maharashtra still offers that concession), registration charges capped at ₹30,000 for anything above ₹30 lakh, GST if the property's under construction, and the builder's own charges for society formation, parking, and maintenance deposits.
Here's the part that catches people off guard: stamp duty isn't calculated on whatever price you negotiate. It's calculated on whichever is higher, your agreement value or the government's Ready Reckoner rate for that area. So you can negotiate the builder down by a few lakhs and still pay stamp duty as if you hadn't. Worth confirming the current Ready Reckoner rate before you do your maths, not after.
Ask for the Carpet Area, Not the "Super Built-Up" Number
For years, builders in Mumbai sold flats based on super built-up area, a number that included staircases, lobbies, and common spaces you'd never actually stand in. RERA cleaned this up by requiring carpet area to be quoted, the real, usable floor space inside your own walls.
Still, ask directly: what's the RERA carpet area for this specific unit? Two flats both labelled “2 BHK” in the same building can differ by a surprising amount once you compare actual carpet area against price per square foot.
Go See the Site, Not Just the Sample Flat
The show flat is designed to sell you a feeling. It's furnished beautifully, lit perfectly, and tells you nothing about the building you'll actually move into. Visit the real site, once in the evening and once during the day, since traffic, noise, and light change completely between the two. If neighbouring towers are already occupied, test the lifts and check water pressure yourself rather than taking the broker's word for it. Walk the surrounding lanes too. The distance to a decent grocery store or your kid's school will matter to you far more on an ordinary Tuesday than the clubhouse you saw in the brochure.
Look Up What the Builder Has Actually Delivered Before
A builder's past projects tell you more than anything in their current sales pitch. Find one of their older completed buildings and talk to the people actually living there, not the sales office. Ask if possession came on time. Ask what happens when something breaks. Ask if RERA complaints have ever been filed against them; that information's public if you look.
This matters even more right now, with so many new projects in Borivali West launching almost back to back. A handful of solid builders and several newer, less established ones are all building within shouting distance of each other, promising roughly the same things. Location alone won't save you from a builder who doesn't deliver.
Read the Agreement Like It's the Only Thing That Protects You
Because it is. The builder-buyer agreement, not the brochure, is what actually holds up if something goes wrong. Check the penalty clause for delayed possession, and whether it works both ways, does the builder owe you for delays the same way you'd owe them for late payments? Check that fittings and finishes are specified by brand and model, not vague phrases like “premium quality.” Check the defect liability period. If anything reads vague, ask for it in writing before you sign, not after.
Run the EMI Numbers Against Your Real Life, Not Your Loan Eligibility
Banks will usually approve more than what's comfortable for your actual monthly budget. Before locking into a flat at the very top of what you qualify for, sit down and calculate the EMI against your real expenses. If it's an under-construction property, you'll likely be paying pre-EMI on the loan while still paying rent somewhere else, so budget for both running at once for a while.
Think Past Today, Even If You're Buying to Live In It Forever
Plans change. Ask yourself honestly: if you had to sell or rent this out in five years, would there be demand? A new apartment in Mumbai in a well-connected, established neighbourhood with genuine end-user demand tends to hold its value far better than something in a purely speculative, investor-heavy pocket.
Last Word
None of this is complicated on its own. RERA checks take ten minutes. Reading an agreement properly takes an afternoon. But buyers skip these steps all the time because everything else about buying a flat feels urgent and emotional, and these quieter checks feel like they can wait. They can't. Slow down just enough to actually look, and you'll save yourself the kind of headache my friend spent four months trying to avoid.