Good record-keeping rarely feels urgent until the day you need to calculate a Capital Gains Tax bill, defend a figure during an HMRC enquiry, or prove exactly what you paid for an asset bought fifteen years ago. Because Capital Gains Tax is calculated on the difference between what you paid and what you received, missing or incomplete records can mean paying more tax than necessary, or facing HMRC penalties for a return that cannot be evidenced.
The Core Records Every Disposal Needs
For any chargeable asset, you should keep the purchase contract or invoice, the completion statement showing the final price paid, evidence of any professional fees paid to acquire the asset such as solicitor or agent fees, and the equivalent sale-side documents when you eventually dispose of it. Bank statements showing the actual payment can also help confirm the figures used in your calculation.
Property-Specific Records
For property, HMRC also expects evidence of the purchase price, Stamp Duty Land Tax paid, and any capital improvements made during ownership, such as an extension or a loft conversion, as opposed to routine repairs and maintenance, which are not deductible. Keep invoices from builders and tradespeople, planning permission documents, and before-and-after evidence where possible, since improvement costs are one of the most commonly disallowed claims when evidence is weak.
Records for Shares and Investments
Shareholdings bring their own complexity, particularly where shares were acquired at different times and prices, through dividend reinvestment, or via corporate actions such as mergers, demergers, or rights issues. Contract notes from every purchase and sale, annual investment statements, and records of any reinvested dividends should all be retained, since HMRC’s share matching rules require you to identify precisely which shares were sold and at what original cost.
Records for Inherited or Gifted Assets
Where an asset was inherited, your base cost is normally its probate value rather than what the deceased originally paid, so a copy of the probate valuation or grant of probate is essential. Where an asset was gifted to you, particularly by a connected person such as a family member, you may need evidence of its market value at the date of the gift, since gifts between connected persons are usually treated as a disposal at market value rather than the price actually paid.
How Long Should You Keep These Records?
As a general rule, records supporting a Self Assessment return should be kept for at least 22 months after the end of the tax year to which they relate, or 5 years and 10 months if you are in business or file later. In practice, because base cost records for property and shares can be needed decades after purchase, it is far safer to keep original purchase documents for as long as you hold the asset, rather than relying on the minimum statutory retention period.
What Happens If You Cannot Evidence a Figure?
Where records are missing, HMRC may not accept your claimed figures at face value, particularly for improvement costs or historic acquisition values. This can result in a higher taxable gain than is actually accurate, and in some cases can trigger a formal compliance check if HMRC considers the figures used to be unsupported or implausible.
Conclusion
Capital Gains Tax is ultimately a tax on evidence as much as it is a tax on profit. Keeping organised records from the moment you acquire an asset, rather than trying to reconstruct them years later at the point of sale, is one of the simplest ways to protect yourself from paying more tax than you legally owe.
People Also Ask
How long do I need to keep Capital Gains Tax records?
At least 22 months after the end of the relevant tax year, though for property and shares it is safer to keep original purchase records for as long as you own the asset.
Can I claim improvement costs without receipts?
HMRC generally expects documentary evidence such as invoices for any improvement costs claimed, and unsupported claims are more likely to be challenged.
What value do I use for an inherited asset?
Normally the probate value at the date of death, which should be supported by the grant of probate or the formal estate valuation.
