Tax and SARS knowledge base

What records prove base cost for CGT?

What records prove the base cost of shares or another investment for CGT?

Last reviewed: 28 August 2026

Direct answer

Base cost is the amount measured against disposal proceeds to work out whether a capital gain or loss arose. The strongest proof is a document trail showing how you acquired the asset, what qualifying costs were incurred, how corporate actions affected it and what happened when it was disposed of. Keep a running schedule that points to the actual records, not a single number copied from an app.

SARS says base cost can include qualifying acquisition, enhancement and disposal expenditure that has not already been allowed as a deduction from income. That means the document must establish both the amount and why it qualifies. A general estimate, a current account balance or a recollection years later is weak evidence.

What this means in practice

Create an evidence folder at acquisition, not when you decide to sell. For shares, save the contract note, brokerage confirmation, broker statement and any allocation evidence. For other investments, save the purchase agreement, invoice, transfer documents and costs directly connected with acquiring the asset. Label documents with the asset, date and ownership percentage.

Then preserve the events that change the holding. Corporate actions can affect quantity, base cost or the identity of an asset. Keep notices for rights issues, unbundlings, mergers, share consolidations, returns of capital, reinvestments and portfolio transfers. If a provider changes, download historical records before the old account closes. A later broker may show an opening value, but it may not know the tax base cost.

When you sell, retain the sale contract, fees and settlement evidence. Prepare a schedule that shows proceeds, base cost and the supporting document reference. Make adjustments transparent. For example, if an amount is a corporate-action adjustment, name the event and attach the issuer notice. Do not put private costs, ordinary investment-management charges or an expense already deducted from income into the schedule simply because it was paid while you held the asset.

The schedule should be updated after each material event, not rebuilt from memory at return time. This is particularly valuable when a holding is sold in part over several years. For identical listed shares, the selected identification and base-cost method must be supported and consistently applied. A broker tax certificate is helpful evidence but does not eliminate the need for your own acquisition history.

Step-by-step

Create an asset record.

Give every investment a clear name and include its acquisition date, quantity, owner and account. Store the original purchase evidence in the file.

Capture qualifying costs as they arise.

Keep invoices, contract notes, professional invoices and other documents that show direct qualifying acquisition, enhancement or disposal costs. Note whether any amount was claimed elsewhere.

Record corporate actions and changes.

Add issuer notices, broker notices, transfers and partial sales to the file as they occur. Update the schedule immediately while the information is available.

Reconcile with statements.

Compare the schedule to periodic broker or provider statements. Investigate differences in quantity, dates or values instead of assuming that an app total is the tax result.

Prepare the disposal calculation.

On sale, record supported proceeds, fees and allocated base cost. Keep the complete trail that leads to the final gain or loss.

Retain the return file.

Store the final calculation, ITR12, ITA34 and supporting evidence together. This is the practical file to use if SARS asks for documents.

Documents and records to keep

Purchase contract notes, agreements, invoices and brokerage confirmations.
Corporate-action, transfer, valuation and portfolio statements.
Proof of qualifying direct expenditure and sale costs.
A running base-cost schedule with document references.
ITR12, assessment and any SARS verification correspondence.

Important limits and exceptions

Not every cost connected with an investment is base cost. SARS notes that current costs such as interest, repairs, insurance and rates are normally either income deductions or personal costs, rather than base cost. Do not include an expense twice, and do not assume a provider's market-value display is an acquisition-cost record.

Different rules can apply to pre-2001 assets, inherited or donated property, employee shares, connected-person dealings and foreign holdings. Where an asset is complex, preserve the evidence and obtain advice before committing to a calculation.

When to get tailored advice

Seek advice if records are missing, a portfolio was moved between brokers, there are corporate actions, holdings were acquired before 2001, or the proposed base cost is material. TaxProof can help produce an evidence index and reconciliation schedule, but a professional should review a disputed or complex valuation.