Option tax treatment depends on the instrument and event: acquiring, selling, closing, expiring or exercising an option are not interchangeable. Employment-related options and spread bets can sit outside a straightforward investment-CGT workflow.
Keep event-level records
Retain contract identifiers, open and close dates, premiums, fees, quantity, strike, expiry, exercise details, underlying shares received and GBP conversion. An exercise may affect the allowable cost and acquisition date of resulting shares.
Classify the event before calculating it
| Event | Question to resolve |
|---|---|
| Purchase or grant | Was the option acquired as an investment or through employment? |
| Sale or closing trade | Which contract was disposed of, and what premium and fees applied? |
| Exercise | What shares were acquired, when, and what amount enters their CGT cost? |
| Assignment | Who exercised and what legal obligation was settled? |
| Expiry or lapse | Does the instrument and circumstance create an allowable loss? |
For employee share options, HMRC's 2026 HS287 helpsheet says the CGT cost of shares acquired on exercise can include the option cost, exercise price and amounts charged to Income Tax. It also notes that an unexercised option that lapses does not create an allowable CGT loss in the circumstances covered by that guidance.
FiscalFox scope
Some broker importers recognise supported exchange-traded option rows. Unsupported or ambiguous activity must be reviewed; the presence of an imported row is not a conclusion that CGT applies. FiscalFox does not determine employment-tax treatment or guarantee coverage of every option strategy.
Broker labels are not legal classifications
A row labelled “exercise”, “expiry” or “cash settlement” can omit facts needed to determine tax treatment. Reconcile the broker export with contract notes, award documentation, payroll records and the resulting share position. Where exercise creates ordinary shares, keep the option evidence with the later share-disposal records.
Illustrative exercise record
Suppose an employee pays £2 per share to exercise an option over 1,000 shares and £3,000 is charged to Income Tax on exercise. Before considering any other adjustment, HS287 indicates that the CGT cost of the acquired shares can include the £2,000 exercise price plus the £3,000 amount charged to Income Tax, as well as any amount paid for the option. That record is different from simply importing 1,000 shares at the market price shown by a broker.
Retain the option agreement, exercise confirmation, payslip or P60 evidence of the taxable amount, acquisition date and any amount paid for the option. The example is not a conclusion for every award: restricted securities elections, tax-advantaged plans, employer National Insurance arrangements and non-UK employment facts can change the analysis.
When specialist review is sensible
Seek advice for employee options, assignments, complex multi-leg strategies, non-sterling exercise events, restricted securities or instruments whose legal nature is unclear. Use the calculator only after the transaction type and taxable event have been established.
Official UK tax references
This guide is checked against published GOV.UK and HMRC material. FiscalFox is a calculation tool, not personal tax advice; review unusual transactions with a qualified adviser.