You bought 50 shares of a mid-cap at ₹800 each. Total outlay: ₹40,000. You wake up one morning, open your broker app, and there are now 100 shares sitting in your portfolio — each showing ₹400. The total value is still ₹40,000. Nothing changed. Or so it looks.
What actually changed is buried in the fine print, and it matters a lot when you sell.
The Basic Mechanics — Same Outcome, Different Path
A 1:1 bonus issue means the company gives you one free share for every share you already hold. Your count doubles, the price halves. A 1:2 stock split means every share you hold becomes two shares, each worth half. On your broker screen on the morning after either event, the result looks identical.
But the mechanics are completely different. A bonus issue involves the company issuing new shares out of its reserves — effectively converting retained earnings into paid-up capital. A stock split just subdivides the existing shares. No new capital is created, no reserves are touched.
For most retail investors, this distinction feels academic — until tax season.
What Zerodha (and Every Other Broker) Shows You
On the ex-date morning, your holdings screen will reflect the new quantity and the adjusted price. If you're on Zerodha, the P&L tab will show the average buy price recalculated. On Groww or Angel One, same thing.
Here's where it gets confusing: the display looks the same for both events, but the underlying cost-basis calculation the broker uses is different — and brokers often get this wrong in their P&L view, which is why you should always cross-check with your actual contract notes and your chartered accountant when filing ITR.
Your CDSL or NSDL statement (the CAS, or Consolidated Account Statement, that hits your email every month) will show the new shares credited. For a bonus issue, you'll see a credit entry with zero value. For a split, the original holding gets adjusted in-place.
The Tax Math — This Is Where It Actually Diverges
This is the part that trips up most retail investors.
Bonus shares:
Under Section 55(2)(aa) of the Income Tax Act, the cost of acquisition of bonus shares is treated as zero. That's not a simplification — it's the law. So when you sell those 50 bonus shares (in the 1:1 example above), your entire sale proceeds are treated as capital gains.
Say you got those 50 bonus shares in April 2025, and you sell them in May 2025 for ₹420 each. That's ₹21,000 in proceeds. Your cost: ₹0. Your short-term capital gain: ₹21,000. Tax at 20% (post Budget 2024 rates for listed equity): ₹4,200.
Now the FIFO catch: when you eventually sell shares from this holding, the Income Tax department uses First In, First Out. Your original 50 shares (cost ₹800 each) get sold first on paper. The zero-cost bonus shares come next. This sequencing affects whether you're in short-term or long-term territory — because the holding period of bonus shares starts from the date of allotment, not your original purchase date.
Stock split:
Here, the cost of acquisition gets proportionally adjusted across the new shares. If you paid ₹800 for one share and it splits 1:2, you now have two shares with a cost of ₹400 each. Your total cost basis hasn't changed — ₹40,000 is still ₹40,000 — it's just spread across more shares.
When you sell post-split, the capital gain calculation uses this adjusted ₹400 as your cost. And critically, the holding period doesn't reset. If you'd held the original shares for 13 months before the split date, those post-split shares still carry that 13-month history. Long-term capital gains treatment (10% above ₹1.25 lakh threshold, as per current rules) applies based on the original purchase date.
Why Indian Companies Prefer Bonus Issues
Splits are relatively rare on Indian exchanges. Bonus issues are the corporate action of choice here. Reliance Industries did a 1:1 bonus in 2017. Wipro has issued bonuses multiple times over the decades — it's practically a tradition. Infosys has done both bonuses and splits at various points.
Why the preference? A few reasons. Bonus issues signal that the company has healthy reserves — it's distributing accumulated profits as shares rather than cash. It also has a psychological effect on retail participation: a ₹3,000 stock becomes a ₹1,500 stock after a 1:1 bonus, which feels more accessible even if the market cap is identical.
Stock splits in India are more common among newer-age companies or those with very high face values. When MRF trades above ₹1.2 lakh per share, a split would make obvious sense — but MRF has famously resisted, making it a collector's item among retail investors.
The Record Date Trap
Here's a practical mistake retail investors make repeatedly. You see a bonus issue announced with a record date of, say, 18 April 2026. You think: buy before 18 April, get the bonus shares.
Correct logic, wrong execution window. In Indian markets, the settlement cycle is T+1. So if the record date is 18 April, you need to be holding the shares as of end-of-day 17 April — which means you must have bought on or before 16 April (assuming both are trading days) for the purchase to settle in time.
Miss this by one day and you'll buy the stock ex-bonus at the adjusted lower price but receive zero bonus shares. You haven't lost money in absolute terms, but you've paid the pre-bonus price without the pre-bonus benefit — and you'll see a day-one notional loss on your screen when the price adjusts.
The NSE and BSE both publish ex-dates clearly on their corporate actions page. Check there, not just your broker's notification.
What You Should Actually Do After a Corporate Action
First, don't panic when your portfolio looks "down." The morning-after price adjustment is mechanical — your wealth hasn't changed.
Second, download your updated CAS from CDSL or NSDL within the week. Verify that the new shares have been credited correctly. Errors are rare but not unheard of.
Third, note the allotment date for bonus shares in your records. This is the date the holding period clock starts for those shares — relevant for the 12-month LTCG threshold on listed equity.
Fourth, if you're planning to sell any portion of the holding after a bonus issue, run the FIFO math before you do. Selling a smaller lot that you assume is "the bonus shares" may not work the way you expect — the tax department looks at the transaction chronologically, not by which shares you think you're selling.
Finally, reconcile your broker's P&L display with your own calculation at least once. Platforms show average cost differently, and a wrong average cost in your broker's UI doesn't change your actual tax liability. Your contract notes and the original purchase records are ground truth.
The bottom line: bonus and split look the same in your app, but they are not the same on your ITR. A ₹0 cost basis on bonus shares is a hidden tax liability building up in your portfolio. Know exactly what you're holding before you hit sell.