Reporting options on Self Assessment (SA108)

Research snapshot

Use this page in January, or better in April, when the year's option trades have to become boxes on a form. It covers which pages of the return you need, which section options belong in, what HMRC expects you to attach, and the three timing rules that catch options writers.

Do you need the Capital Gains pages at all?

The SA108 notes say to fill in the Capital Gains Tax summary pages if you sold or disposed of chargeable assets worth more than £50,000, if your chargeable gains before losses were more than the £3,000 annual exempt amount, or if you want to claim an allowable capital loss. Any one of the three is enough. The box numbers on this page are from the 2026 edition of the notes, which covers the 2025/26 return; HMRC publishes the 2026/27 edition in spring 2027 and the structure rarely moves, but check it before you file.

An options writer trips these tests earlier than a share investor expects, because of TCGA 1992 s.144(1): granting an option is itself the disposal of an asset, and HMRC CG55536 makes the premium a gain arising when the option is written. Every premium you collect is a disposal, dated the day you sold the option, whatever happens afterwards. Twelve monthly covered calls are twelve disposals. Add the shares that get called away or put to you, at their full value, and the £50,000 proceeds test is crossed by a modest account in a single active year.

Which section of the SA108 options belong in

The form has separate sections for residential property, "other property, assets and gains", listed shares and securities, and unlisted shares. The notes define listed shares and securities as shares or securities from a company listed on a recognised stock exchange, shares in a UK open-ended investment company, and units in an authorised unit trust. An option is none of those. It is a contract with a counterparty, not a share or security of a company, so option gains and losses go in the section most readers skip past:

Shares that arrive through the option are different. When a covered call is assigned, or a cash-secured put puts shares to you and you later sell them, the share disposal goes in the Listed shares and securities boxes 23 to 26, with the option premium folded into that share computation by s.144(2) rather than reported twice. The worked examples show both halves in pounds.

Computations must be attached, and HMRC's own working sheet will not do

The notes are explicit: "You must send us your computations, valuations, specified claim forms and any working sheets with the Capital Gains Tax summary pages of your tax return." A computation is a short calculation for each asset showing the disposal date, the proceeds, the allowable costs and the resulting gain or loss. The boxes carry the totals; the computations carry the evidence.

The notes also say you cannot use the working sheet on page CGN 15 if "you got your asset by the exercise of an option". Shares acquired by exercising a call, or by having a put assigned to you, need their own written computation, because the option premium has to be folded into the share cost under s.144(2) and the working sheet has no line for it. In practice that means one computation per option series and one per share holding that an option touched, and a schedule that ties them together (a template is below).

Online filing accepts the computations as a PDF attachment. Keep the schedule in a spreadsheet through the year and export it; do not try to reconstruct it from broker statements in January, because the tax points are not the dates a broker statement highlights.

The grant-date rule on the form: three timing traps

1. The March grant. A put written on 20 March 2027 is a 2026/27 disposal even if it does not expire until April. Its premium goes in box 15 of the 2026/27 return. If it lapses in April, nothing further is reported: CG55536 says a lapse has "no effect on the grantor". If you had already filed, nothing changes.

2. The buy-back after you filed. If you buy that option back in May 2027 instead, the purchase is not a new disposal. TCGA 1992 s.148 disregards it and adds its cost to the incidental costs of the March grant, and CG55545 confirms relief is immediate. The 2026/27 computation for that grant is now different, so if the return has gone in you amend it. HMRC's guidance allows a correction within 12 months of the 31 January filing deadline, so a 2026/27 return can be amended online until 31 January 2029; after that the route is a written overpayment-relief claim, which has to be made within four years of the end of the tax year.

3. The assignment after you filed. If the option is exercised against you in a later year, s.144(2) merges the grant with the share purchase or sale into one transaction, and CG55536 says any tax already paid on the premium "should be set off or repaid". Same mechanics: amend the earlier year if it is inside the window, otherwise claim.

Losses: claim them or lose them

A lapsed long option, a long option sold for less than it cost, or a written option bought back for more than its premium produces an allowable loss. TCGA 1992 s.16(2A) says a loss "shall not be an allowable loss unless, in relation to that year, he gives a notice to an officer of the Board quantifying the amount of that loss", and that the notice is treated as a claim, which brings in the time limit in TMA 1970 s.43: no claim "may be made more than 4 years after the end of the year of assessment to which it relates". Entering the losses on the SA108 is the notice. A trader who lets a dozen long options expire worthless and never reports them has no losses to carry forward.

• Box 19 takes the year's losses on other assets, which is where lapsed and loss-making options sit.
• Box 47 carries unused losses forward.
• Box 45 uses losses brought forward, and only down to the £3,000 annual exempt amount, never below it.

Losses of the year come off gains of the year before the annual exempt amount is applied; brought-forward losses are used only to the extent gains exceed £3,000. Order matters when you are deciding whether a year needs a loss claim at all.

Which exchange rate HMRC accepts for dollar trades

Most UK retail options activity is in US dollars, and every leg has to be expressed in sterling in the computation. HMRC's Capital Gains Manual at CG78310 does not prescribe a reference point for the exchange rate; it expects "a reasonable and consistent method". The spot rate on the day of each event, or HMRC's own published monthly rates, are both reasonable. What is not reasonable is switching between them to flatter the answer.

• Each leg converts on its own date: a premium collected in March at one rate, a buy-back in May at another. A dollar profit can be a sterling loss, and the reverse.
• A broker's "realised P&L in GBP" report often converts both legs at the closing date's rate. That is not the HMRC method and will not match your computation.
• A foreign currency bank account has been outside CGT for an individual since 6 April 2012 (TCGA 1992 s.252). A broker's client-money balance is a debt owed to you rather than a bank account and the position is less clear, so keep the computations leg by leg and do not try to net the wallet.

A computation schedule you can copy

One row per tax event, kept from the first trade. The last column is what turns the schedule into the return. Figures below are the library's own worked examples, so you can trace each one.

Columns to add for a dollar account: the currency amount, the rate used and its source, and the sterling result. Columns to add for every account: the commission per leg, and for UK deliveries the 0.5% SDRT paid on the share purchase (STSM113030), which is an allowable cost of the shares.

What a broker's report does not do for you

• It dates a written option's profit to the close or expiry, not to the grant, so March grants land in the wrong tax year.
• It nets a buy-back against the original credit as one trade; the return wants the buy-back as an incidental cost of the grant, which is the same money but a different line and sometimes a different year.
• It converts at its own rate, usually the closing day's, for both legs.
• It does not know that a lapsed long option only becomes a loss when you claim it, or that shares acquired by exercise carry the premium in their cost.
• It rarely shows SDRT as a separate allowable cost on UK deliveries.

The report is still useful: it is the audit trail for dates, prices and contract sizes. It is not the computation.

Before 31 January

1. Total the year's disposal proceeds: every premium received, every long option sold or settled, every share delivery. Over £50,000, or gains before losses over £3,000, or a loss to claim: the pages are needed.
2. One computation per option series and per share holding an option touched. Attach them.
3. Options in "Other property, assets and gains"; shares delivered through options in "Listed shares and securities".
4. Every loss quantified and entered in the year it arose; carry the unused balance to box 47.
5. One exchange-rate method, stated in the computations, used for every leg.
6. Open March grants noted, with a diary entry to amend if a buy-back or assignment follows.
7. Rates for the year confirmed on gov.uk: 18% on the slice within your unused basic-rate band, 24% above it, £3,000 annual exempt amount for 2026/27. The Self Assessment walkthrough covers the rest of the return.