What Records Should I Keep for Capital Gains Tax

Capital Gains Tax only applies to the gain you make, not the sale value itself. That means your ability to claim deductions depends on how good your records are. Many people end up paying more tax than necessary because they cannot fully prove their costs. HMRC accepts a wide range of documents, but the burden is on you to keep and store them correctly. This article explains everything you need to keep for shares, crypto, property, business assets and personal possessions.

Why Good Records Matter for Capital Gains Tax

You pay Capital Gains Tax on the profit you make when you dispose of an asset. To work that out correctly you need to know:

• what you paid for the asset

• what you sold it for

• what you spent improving or buying or selling it

• any associated fees or charges

Without documentation, HMRC can challenge your figures. If you cannot prove your costs they may disallow them which increases your taxable gain.

In my opinion good records often reduce tax more than people expect because small forgotten costs add up quickly.

Key Records HMRC Expects You to Keep

HMRC requires you to keep any evidence that supports your Capital Gains Tax calculation. The exact records depend on the type of asset.

1. Records for Shares and Investments

If you buy and sell shares, funds or ETFs you should keep:

Purchase records

• contract notes

• broker statements

• purchase confirmations

• date the asset was acquired

• number of units or shares bought

• total paid including fees

Sale records

• contract notes

• sale confirmations

• broker statements

• disposal date

• number of units sold

• total sale proceeds

Associated costs

• broker fees

• platform charges

• stamp duty

• foreign transaction fees

• transfer fees

Dividend reinvestment statements

If you use dividend reinvestment, these purchases affect the calculation of your average share pool. Keep every reinvestment record.

In my opinion most CGT errors on shares happen because people forget to include fees or reinvestments.

2. Records for Cryptocurrency

Crypto is treated as a taxable asset, so HMRC expects the same level of detail as shares. Keep:

Transaction history

• full buy and sell history

• date and time of each trade

• quantity of tokens

• price at the time of the transaction

• exchange fees

Wallet to wallet transfers

Even though transfers are not taxable, proof of wallet ownership helps show you did not dispose of assets.

Staking or reward records

Rewards may be taxable as income and change your CGT cost basis.

In my opinion crypto traders should always download their exchange reports annually because platforms sometimes delete old data.

3. Records for Property (including rental property and second homes)

Property Capital Gains Tax requires more documentation than almost any other asset. Keep:

Purchase records

• completion statement

• solicitors’ invoices

• stamp duty receipts

• survey fees

• mortgage arrangement fees (if deductible)

• legal fees

Improvement records

These must be capital improvements not repairs. Keep:

• invoices

• receipts

• contracts

• before and after evidence if possible

Examples of improvements:

• extensions

• new kitchens where layout changes

• loft conversions

• structural changes

• adding a garage or outbuilding

Repairs cannot be claimed, so evidence must show the work improved the property.

Sale records

• estate agent invoices

• solicitors’ fees

• marketing fees

• final completion statement

Occupancy evidence

If you claim Private Residence Relief or periods of deemed occupation, keep:

• council tax records

• utility bills

• tenancy agreements

• bank statements showing you lived there

4. Records for Personal Possessions Worth Over £6,000

This includes artwork, antiques, jewellery or collectables. Keep:

• purchase receipts

• valuation reports

• auction fees

• restoration invoices

• sale receipts

If an item increases in value significantly, these records matter more than people expect.

5. Records for Business Assets

If you sell or dispose of business assets:

• invoices showing purchase

• depreciation schedules

• records of improvements

• any associated selling costs

If you claim Business Asset Disposal Relief, evidence showing your ownership and involvement in the business is essential.

How Long You Must Keep Capital Gains Tax Records

HMRC requires you to keep records for:

• at least 5 years after the 31 January filing deadline

Example:
For the 2024 to 2025 tax year, you must keep records until at least 31 January 2031.

For property and business assets, I personally recommend keeping records indefinitely because you never know when you will need to calculate a future gain.

What Happens If You Cannot Provide Records

If HMRC opens an enquiry and you cannot provide evidence:

• they may disallow your claimed costs

• they may increase your taxable gain

• they may challenge your valuation

• you may face penalties for careless record keeping

In my opinion this is one of the easiest ways people accidentally overpay tax.

You can recreate some records, but it is harder:

• contact your solicitor for completion statements

• ask your broker for historical statements

• request duplicates from traders or contractors

• check your emails for receipts

• use bank statements to prove payments

Recreated records are accepted if they are complete and reasonable.

Digital vs Paper Records

HMRC accepts both formats.

Digital records

• cloud storage

• scanned receipts

• downloaded broker reports

• photos of invoices

• spreadsheets

Paper records

• physical receipts

• original contracts

• printed statements

Digital records are easier to store long term. In my opinion the safest method is to scan or photograph everything the day you receive it.

Specific Records You Must Keep for Different CGT Reliefs

Private Residence Relief

If you claim part of a property was your main residence:

• evidence of living there

• mortgage statements

• driving licence address

• utility bills

Letting Relief

Only applies in specific cases. Keep evidence of renting the property out.

Business Asset Disposal Relief

You must keep records proving:

• trading activity

• ownership

• involvement in the business

• disposal details

Gift Hold-Over Relief

If gifting business assets keep:

• valuation evidence

• signed agreements

• records of recipient details

What Records You Must Submit to HMRC

Most records are not submitted automatically. You only file:

• the Capital Gains Tax figure

• the supporting calculation

• the 60 day return if needed

• your Self Assessment return

HMRC requests your records only if they open an enquiry.

How To Organise Your Records Easily (My Personal Recommendation)

In my opinion the simplest system that protects you from stress later is:

1. Create folders by tax year

Have a folder for each year on your computer or cloud storage.

2. Create subfolders for:

• shares

• crypto

• property

• business assets

• personal possessions

3. Save every document immediately

When you buy or sell something save:

• receipts

• invoices

• statements

• screenshots

• emails

4. Keep a master spreadsheet

List:

• purchase date

• sale date

• cost

• sale value

• fees

• improvement costs

• total gain

5. Back everything up

Use a cloud service and one offline backup.

By doing this you never need to search for documents again.

Real World Examples

Example 1: Shares

Emily sells shares bought ten years earlier. She kept only the sale documents, not the purchase ones. Without proof of original cost HMRC taxed her on the full sale proceeds. An accountant eventually retrieved old broker statements which reduced her gain by half.

Example 2: Rental Property

Tom sells a rental property. He forgot about £12,000 of improvement work done five years earlier and could not find the receipts. Eventually he contacted the contractor who supplied duplicates. This reduced his Capital Gains Tax bill significantly.

Example 3: Crypto

A trader loses access to data after an exchange closes. Without downloaded statements, rebuilding the history takes weeks. He now downloads his transaction logs monthly.

Example 4: Artwork

Sarah sells a painting inherited years ago. She keeps valuation reports which help avoid an incorrect gain calculation.

Conclusion

Capital Gains Tax relies completely on accurate record keeping. You must keep proof of your purchase costs, selling costs, improvement costs and anything else that affects your gain. HMRC requires you to keep these records for at least five years after the filing deadline, but in my opinion keeping them indefinitely is safer, especially for property.

Good records reduce your tax bill, protect you during HMRC enquiries and make calculating CGT far easier. Whether you hold shares, crypto, property or business assets, keeping organised records is one of the best ways to avoid unnecessary tax.