Capital Gains Tax Calculator

The gain is not the difference between what you paid and what you sold for. Dealing costs come off both ends, an allowance may apply, and losses from elsewhere in the portfolio can be set against it. This works through to the figure that actually leaves your account.

Your inputs

Your result

You keep—Proceeds after selling costs and tax.

Tax due—

Gross gain—

Taxable after losses and allowance—

Tax as a share of the gain—

Return before tax—

Return after tax—

Formula

Gain = proceeds − costs of sale − purchase price − costs of purchase. Tax = (gain − allowance) × rate, with losses carried in first.

What counts as the gain

The taxable gain is the sale proceeds less the cost of selling, less what you paid, less the cost of buying. Commission at both ends and any transaction tax paid on purchase are part of the acquisition and disposal cost in most systems, and leaving them out overstates the gain.

Losses realised elsewhere generally come off before the allowance, and unused losses can usually be carried forward. Both reduce what is taxed rather than what is owed, so their value depends on your rate.

The rate varies enormously

Flat rates are common in continental Europe: around a quarter to a third of the gain, sometimes with a lower rate for government bonds. Several countries instead add the gain to income and tax it on the ordinary scale, which means the rate depends on what else you earned that year. A few apply a lower rate the longer the asset was held, and a few tax nothing at all after a qualifying period.

Enter the rate that applies where you are tax resident. The figure is not a detail: the difference between 19% and 42% on a 30,000 gain is nearly 7,000.

The wrapper often matters more than the rate

Many countries have accounts in which gains are either untaxed, taxed at a reduced rate, or deferred until money leaves the account. Selling inside such an account and selling outside it can produce very different outcomes from the same trade. Check which applies before assuming a sale is taxable at all.

When the tax falls due

Tax is normally triggered by the sale, not by the gain existing. An unrealised gain costs nothing, which is why the timing of a disposal is itself a decision — particularly near the end of a tax year, or in a year when income is unusually low or high.

What this does not do

It does not apply an inflation adjustment, which a few systems still allow on long holdings. It does not handle partial disposals where an average cost has to be worked out across several purchases. And it assumes one rate throughout; where gains are added to income and cross a threshold, part may be taxed at one rate and part at another.

Frequently asked questions

Are dealing costs deductible?

In most systems yes. Commission on purchase forms part of the acquisition cost, and commission on sale reduces the proceeds. Both lower the taxable gain.

Can I use losses from other investments?

Generally yes, against gains in the same year, and unused losses can usually be carried forward. The rules on which losses can offset which gains differ by country.

What rate should I enter?

The rate on investment gains where you are tax resident. Some countries use a flat rate, others add the gain to income and tax it on the ordinary scale.

Do I owe tax if I have not sold?

In most systems the tax is triggered by the disposal, not by the gain existing. A few tax unrealised gains inside particular account types.