How to find price paid for shares

[Molecule]

My mother has been in a care home for nearly three years. She is self-funding and has an investment portfolio consisting of shares etc which she thought would cover her care costs (she’s nearly 100 so has done pretty well). My sister and I have POA and so far we’ve been able to meet the costs by selling premium bonds, loss making shares and emptying her (many)savings accounts etc. But we are now at a stage of needing to sell some of her larger holdings - shares she’s had for over 30 years and we have no idea how to find when she bought them or what she paid.

We plan to sell the ones initially that will have the least CGT to pay, but need to know what she paid. I can’t find any share certificates and have been through all her papers. I’m loathe to ask her as she will start worrying, and I have a feeling she won’t know. She initially used a stockbroker, but then changed to her bank and now Interactive Investor handles the portfolio, but they’ve no idea of original values.

There is no house to sell - she sold that in the 1990s, gave each of us 4 children a lump sum and invested the rest.

I had to do this recently so I asked ChatGPT and here is the advice it gave me:

1. Check Old Records or Statements

Look through bank statements, brokerage statements, tax returns, or filing cabinets for:
Trade confirmations
Dividend records
Capital gains reports
Any correspondence from brokers or registrars

1. Contact the Broker or Platform Used

If you remember where you bought the shares, contact that broker. They may still have historical transaction data, even from decades ago.
If the broker no longer exists, find out if it was taken over by another company (e.g., many old UK brokers were absorbed by Hargreaves Lansdown, AJ Bell, Barclays, etc.).

1. Contact the Company’s Registrar

If you know the name of the company whose shares you bought, contact their registrar (e.g., Equiniti, Computershare, Link Group).
Provide your full name, previous address(es), approximate purchase date, and National Insurance number (if UK-based).
They might help trace your holdings or issue replacement certificates.

1. Estimate Using Historical Share Prices

If you cannot find records, estimate the purchase price using:
Historical share price data from:
London Stock Exchange archives
Yahoo Finance or Google Finance (for US/UK shares)
Financial Times archives
Try to remember:
Date or year of purchase
Any stock splits or company mergers
Number of shares bought (if you remember)
Example:
If you bought 100 shares of Tesco in 1995 and can find the average price that year was 150p, your cost basis was around £150.

1. Ask Your Accountant or Financial Adviser

If you used one at the time, they may still have tax records or investment documentation.

1. HMRC Guidance (UK-specific)

HMRC allows you to estimate the original cost if you genuinely can’t find it — but you must be reasonable and consistent in your method.
When reporting capital gains, you may need to explain how you estimated your “base cost” if audited.

If you'd like help estimating the historical price of a specific company’s shares, you can ask Chat GPT with the company name and approximate purchase year, and they can estimate it.
Edited to make it easier to read (I just saved the dump a couple of weeks ago, but it looked messy when I pasted it in). Hope that helps.

Gosh! Sorry OP the numbering is still wrong. Hopefully you can make sense of it! By the way we've decided to go with an estimated price based on the average stock price in the approx. year of purchase.

Thank you so much @InSpainTheRain . I’ve just spent two days going through and sorting all her papers, and have finally found something from the original stockbroker that seems to give the amount paid. Not going to save much in CGT

as the shares have increased in value ten fold, but at least we know her care home fees are covered for the next three years.

I’m off to make sure all my papers are filed and easy to find!

No problem @Molecule I know the stress these things cause! Hope you get it sorted!