Capital gains tax is a charge on the profit you make when you sell or otherwise dispose of an asset for more than it cost you. The gain is usually the difference between your sale proceeds and your cost basis, after allowable costs.
It applies to many assets, including shares, funds, property and often crypto, but the rates, exemptions and calculation rules differ by jurisdiction and can change. The tax is triggered by a realised gain, not by price moves you haven’t locked in.
What counts as a taxable gain?
Your gain is typically calculated as sale proceeds minus your adjusted cost basis. Proceeds are what you receive from the sale after selling fees. Cost basis starts with what you paid to acquire the asset, then adjusts for things like commissions, stamp-style purchase taxes where relevant, and certain capital improvements for property.
For listed shares and funds, your cost basis can be affected by corporate actions. Stock splits change the number of shares but not the overall cost, so your per‑share basis adjusts. Mergers, demergers and spin‑offs can require you to allocate your original cost across the new holdings. Return of capital distributions usually reduce basis rather than count as income. The exact treatment is rule based and country specific.
When you sell part of a holding, you need a method to match which units you sold. Common approaches include average cost, first‑in first‑out (FIFO) or specifically identifying the lot you disposed of if your rules allow it. Some jurisdictions impose mandatory share‑matching rules. The method you use affects the reported gain, so consistent record‑keeping matters.
The concept of capital gains is distinct from income. Dividends and interest are usually taxed under income rules, while gains are taxed only when realised. Funds may distribute realised gains to investors; how those distributions are taxed also depends on local law.
When is a gain realised?
A gain is realised when you dispose of the asset. The most obvious disposal is a sale for cash. Others include gifting, swapping one asset for another, redeeming a fund, exercising or being assigned on certain options, and sometimes when an asset becomes worthless. In many places, exchanging one cryptoasset for another is a disposal that can crystallise a gain or loss.
Some accounts or wrappers are designed to be tax efficient. Depending on the jurisdiction, gains inside a pension or retirement account may be sheltered or deferred. Certain savings plans offer allowances that can exempt or postpone capital gains tax on assets held within them. Eligibility, limits and reporting rules vary and change over time.
Currency can matter too. If you buy and sell a foreign‑currency asset, you may need to convert each leg into your tax currency at the relevant dates to compute the gain. Local rules differ on which exchange rates to use.
Short‑term and long‑term treatment
Some countries apply different tax rates to gains based on how long you held the asset. Short‑term usually means a relatively brief holding period and can be treated more like income. Long‑term gains can attract different rates. Other countries apply a single capital gains framework regardless of holding period but may offer reliefs that increase with time held. Always check the rules that apply to you.
Losses, allowances and reliefs
Capital losses can often be used to offset capital gains, reducing the net amount subject to tax. Many systems allow unused losses to be carried forward to future years, sometimes indefinitely, sometimes with limits. Some allow limited offset of capital losses against other income, while others do not.
There may be annual allowances that let you realise a certain amount of gains tax‑free, subject to local thresholds. Reliefs can exist for a primary residence, small business shares, or inheritances, each with specific conditions. Anti‑avoidance rules also exist. For example, if you sell a security and quickly buy it back, a country may disallow the loss or force you to adjust the basis, often called wash‑sale or share‑matching rules. The details differ by jurisdiction and can be updated by tax authorities.
Transaction costs matter. Broker commissions and certain taxes paid on purchase or sale can often be included when working out your gain or loss. Keep all statements and receipts.
Simple examples
Shares: You buy 200 shares at 10.00 each and pay 10 in commission. Your initial cost basis is 2,010. Later you sell the 200 shares at 12.50 and pay 10 to sell, receiving 2,490. Your capital gain is 2,490 minus 2,010, which is 480. If your country uses average cost, that 10 purchase fee is spread across the shares; if it allows specific identification and you sell particular lots, the figures can differ.
Property: You buy an investment flat for 150,000 and spend 15,000 on a new roof that extends its life. Years later you sell for 210,000 and pay 3,000 in selling expenses. Ignoring other factors, proceeds are 207,000. Your adjusted basis is 165,000. The resulting gain is 42,000. Local rules will decide which costs qualify, whether depreciation is required or recaptured, and what reliefs might apply.
Crypto swap: You acquire 1 unit of Token A at 1,000. Later you trade it for 2 units of Token B when Token A is valued at 1,400. In many systems that trade is a disposal of Token A, crystallising a 400 gain. Your basis in Token B starts at 1,400 total, or 700 per unit, before future fees and events.
What traders and investors need to keep on file
Good records make capital gains reporting far easier. Keep trade confirms, statements, contract notes, and any documents for corporate actions. Note purchase and sale dates, quantities, unit prices, fees and any local taxes on transactions. If you hold assets in different currencies, store the exchange rates used on each date. For property, keep invoices that show capital improvements versus routine maintenance.
Brokers and platforms may provide tax reports that summarise disposals, basis and gains according to the rules of a specific country. Formats and assumptions vary by provider and may not capture every nuance, especially around complex actions or transfers between accounts. Check them against your own records, and seek professional advice if your situation is complex. Tax rules vary by jurisdiction and change over time, so always refer to current guidance for your country before filing.