A Specialist Capital Gains Tax Accountant does far more than simply calculate a tax bill after you sell an asset. Their role is to examine the transaction before, during and after disposal, identify the UK Capital Gains Tax rules that apply, check available reliefs and losses, and make sure the gain is reported correctly to HMRC.

For someone selling a property, shares, business, land or another valuable asset, specialist advice can make a substantial difference. In the 2026 to 2027 tax year, the Annual Exempt Amount for most individuals is only £3,000, while the main CGT rates are 18% and 24%. 

Understanding the Real Capital Gain

The starting point is not simply the amount received from a sale. An accountant establishes the chargeable gain by examining the acquisition cost, disposal proceeds, qualifying expenditure, losses and applicable reliefs.

For example, imagine someone purchased an investment property for £220,000 and later sells it for £360,000. The apparent gain is £140,000, but the taxable figure may be lower after allowable costs.

Qualifying costs can include:

• Certain legal and professional fees

• Estate agency costs

• Stamp Duty Land Tax where applicable

• Capital improvement expenditure

• Other costs directly connected with acquisition or disposal

HMRC confirms that qualifying buying, selling and improvement costs can be deducted when calculating a property gain, whereas ordinary maintenance costs generally cannot. 

A specialist accountant checks the evidence behind each deduction rather than automatically accepting every expense supplied by a client.

Checking Which CGT Rate Applies

The CGT rate depends partly on the taxpayer's taxable income. For 2026 to 2027, individuals generally pay 18% on gains falling within the available basic rate band and 24% on gains above it.

This is why an accountant considers the wider tax position rather than looking at the capital gain in isolation.

The Personal Allowance is normally £12,570 and the basic Income Tax band is £37,700 for taxpayers in England, Wales and Northern Ireland, although Scotland has different Income Tax bands.

Identifying Reliefs Before the Sale

One of the most valuable parts of specialist CGT advice is identifying reliefs before a transaction becomes irreversible.

A property owner, for example, may qualify for some form of Private Residence Relief if the property has genuinely been their main home. The calculation can become complicated where the property has been occupied as a home for part of the ownership period and rented out or used differently later.

Similarly, a business owner selling a qualifying business may need advice on Business Asset Disposal Relief.

From 6 April 2026, qualifying gains under Business Asset Disposal Relief are charged at 18%, with a £1 million lifetime limit on qualifying gains.

The accountant therefore asks questions about ownership, trading activities, dates, shareholdings and how the asset was used rather than simply applying a standard percentage.

Reviewing Capital Losses and Previous Transactions

Capital losses can be extremely important when calculating the final liability.

Suppose an investor makes a £50,000 gain on shares but has an allowable £20,000 capital loss from another disposal. Subject to the relevant rules, the loss may reduce the gains on which CGT is calculated.

A specialist accountant will therefore investigate:

• Current year capital losses

• Previously reported allowable losses

• Unused losses brought forward

• Whether losses have been claimed correctly

• Whether losses should be matched against particular gains

This can prevent someone from paying tax on gains that could legitimately have been reduced.

Dealing With Property, Shares and Other Assets

Different assets create different CGT questions. A specialist accountant may deal with:

• Buy to let property

• Land

• Shares and investment portfolios

• Business assets

• Company shares

• Second homes

• Cryptocurrency

• Valuable personal assets

• Assets received through inheritance

Property transactions are particularly time sensitive. Most UK residential property disposals requiring CGT must be reported and paid within 60 days of completion. That deadline is one reason clients should seek advice before completion rather than waiting until their annual Self Assessment return.

How a Specialist Capital Gains Tax Accountant Reduces Risk and Tax Problems

The practical value of a Specialist Capital Gains Tax Accountant becomes even clearer when a transaction involves several assets, changing ownership, a previous residence, an inherited property or a business disposal. The accountant's job is to turn complicated facts into a defensible tax calculation and ensure the reporting requirements are met.

Calculating Property Gains Correctly

Property CGT calculations frequently require considerably more work than subtracting the purchase price from the selling price.

Consider a landlord who bought a property for £250,000 and sells it for £400,000. The initial gain appears to be £150,000. However, suppose qualifying acquisition, improvement and disposal costs total £25,000. The calculation could then begin with a £125,000 gain before considering losses, reliefs and the Annual Exempt Amount.

If the property was previously the owner's main residence, the accountant must examine the occupation history and determine whether Private Residence Relief applies.

This is where dates and documentation matter. A specialist reviews purchase documents, completion statements, invoices and evidence of occupation before finalising the computation.

Advising on Business and Company Share Sales

Selling a business can create one of the largest CGT liabilities an entrepreneur ever faces.

An accountant may need to establish whether the disposal qualifies for Business Asset Disposal Relief, whether the relevant ownership and trading conditions have been satisfied, and whether the £1 million lifetime limit has already been used.

The calculation can also differ depending on whether an individual sells shares, disposes of business assets, or restructures ownership before a sale.

This is an area where obtaining advice before signing the sale agreement can be considerably more useful than asking an accountant to calculate tax afterwards.

Preparing and Filing HMRC Returns

A CGT accountant also handles the compliance side of the transaction.

For relevant UK residential property sales, the taxpayer generally has 60 days from completion to report and pay the CGT due. If the taxpayer is also within Self Assessment, the property disposal normally needs to be reflected in the Self Assessment tax return as well.

For other disposals, reporting may take place through Self Assessment or, where eligible, HMRC's real time CGT service.

The accountant checks:

• Disposal and acquisition dates

• Sale proceeds

• Allowable expenditure

• Reliefs

• Capital losses

• Annual Exempt Amount

• Income tax position

• Amount of CGT payable

• HMRC reporting deadlines

Handling Inherited Assets and Estates

Inherited assets require particular care because the person receiving an asset does not simply inherit the deceased person's original CGT position in the ordinary way.

An accountant may need to establish the asset's value at the relevant date, examine subsequent expenditure and calculate the gain when the beneficiary eventually disposes of it.

There can also be CGT considerations during the administration of an estate. Personal representatives currently have an Annual Exempt Amount of £3,000 for the tax year of death and the following two tax years, subject to the detailed rules governing estates. 

A specialist adviser coordinates these calculations with the wider estate administration and inheritance tax position where appropriate.

Checking the Tax Position Before You Sell

The strongest CGT advice often happens before the disposal.

For example, a client considering selling investments worth £200,000 may have several assets with different gains and losses. Rather than selling everything on the same day without planning, an accountant can model the likely tax position and consider the timing of disposals, available losses and the Annual Exempt Amount.

The £3,000 Annual Exempt Amount is relatively small, so assuming that a disposal will automatically fall below the CGT threshold can be an expensive mistake. 

Tax planning must remain within the legislation, but legitimate planning can prevent avoidable liabilities and reporting errors.

Protecting Clients From Costly HMRC Errors

Finally, a specialist accountant provides a second layer of protection against mistakes.

CGT errors often arise because someone:

• Treats all property expenses as deductible

• Misses an available relief

• Uses the wrong acquisition value

• Ignores earlier capital losses

• Calculates the wrong ownership share

• Misses the 60 day property reporting deadline

• Applies an outdated CGT rate

• Fails to include the disposal in Self Assessment

The rates and allowances change over time, so historical transactions must be calculated using the rules applicable to the relevant disposal date rather than today's figures. HMRC's current guidance confirms that the main individual CGT rates are 18% and 24% from 6 April 2026, while Business Asset Disposal Relief increased to 18% from the same date. 

That combination of calculation, tax planning, relief identification and compliance is what distinguishes a genuine Specialist Capital Gains Tax Accountant from someone who simply enters figures into a tax return.