Total return on a share trade after CGT and transfer stamp duty.
Net return
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Gross gain
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Capital gains tax
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Transfer stamp duty
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What actually lands in your pocket after a share sale
The headline number on a profitable trade flatters you. You buy at one price, sell higher, and the gross gain looks clean. Two charges then quietly reduce it before the money is truly yours. The first is the stamp duty on the transfer of the shares. The second is the tax on the gain. This tool runs both so the figure it shows you, the net return, is what you keep after the Nigerian Exchange and the revenue service have taken their share. It is built for retail investors holding ordinary shares, not for pension funds or traders claiming roll-over relief, both of which follow different rules.
Stamp duty sits on the whole sale value, not the profit
A common surprise is that the transfer duty is charged on the full value of the shares you move, not on the slim profit you made. The rate this calculator applies is 1.5 percent of the disposal value, which is the sell price times the number of shares. So even if your gain were tiny, the duty would still be 1.5 percent of the entire proceeds. That matters most for low-margin trades, where the duty can swallow a meaningful slice of a small gain. Treat this rate as the one modelled here rather than certified law, and confirm the current share-transfer rate with the FIRS (Federal Inland Revenue Service), because the 2025 reform is revisiting several stamp-duty figures.
Capital gains tax now rides on your income band
Nigeria no longer charges a flat rate on share gains for individuals. Instead the gain is stacked on top of your other chargeable income and taxed at whatever personal income tax band it lands in. The practical effect is that two people making the identical gain can pay different tax on it. A person already deep into the higher bands pays more on the same NGN 2 million gain than someone with little other income, because the gain is taxed at their top rate. The calculator captures this by taking the tax on your income with the gain added, then subtracting the tax on your income alone. The difference is the capital gains tax attributable to the trade.
A 100,000-share trade at NGN 40 to NGN 60
Take the worked case the tool opens with. You buy 100,000 shares at NGN 40 and sell at NGN 60, on top of NGN 6 million of other chargeable income. The gross gain is NGN 2 million. The transfer duty, at the 1.5 percent this calculator applies, is 1.5 percent of the NGN 6 million sale value, which is NGN 90,000. The capital gains tax is the extra income tax the NGN 2 million gain triggers: your tax rises from NGN 870,000 on NGN 6 million to NGN 1,230,000 on NGN 8 million, a jump of NGN 360,000. Subtract both charges from the gross gain and your net return is NGN 1,550,000.
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The chart shows the gross gain on the left and the same gain on the right after the two deductions are carved out, so you can see how much of the NGN 2 million survives.
A practical read on whether the trade is worth it
Because the duty is fixed against your sale value and the tax climbs with your income, the same percentage gain is less rewarding for a high earner and for thinly profitable trades. Before you sell, it is worth entering your real other income rather than leaving the default, since that single field changes the capital gains tax materially. If you intend to roll the proceeds straight back into other shares, ask your adviser about reinvestment relief, which can defer the gain and is not modelled here. The tool assumes a straightforward cash-out disposal.
Does the buy-side attract stamp duty too?
Duty attaches to the instrument that transfers the shares, so in practice it bites on the disposal value when ownership changes hands. This calculator applies it on the sale leg only, which is why a falling trade with no gain still shows a duty figure. If your broker also levies transaction fees or exchange charges, those are separate commercial costs and are not part of the tax figures here. Confirm the precise point of charge with the FIRS, since the reform is tidying up how stamp duty applies to securities.
What happens if I sell at a loss?
If your sell price is below your buy price the gross gain is negative, there is no capital gains tax because there is no gain to tax, and the net return the tool shows simply reflects your loss less the transfer duty on the sale. Capital losses on shares are not refunded as cash, and the rules on whether a loss can shelter other gains are narrow, so do not assume a loss creates a tax saving. Check the current loss-relief position with the FIRS before relying on it.