Who operates FiscalFox
FiscalFox was founded by Grant Sloane and is developed and operated by Rolling Sloane Technology Limited, a company registered in England and Wales under company number 16659202. Its registered office is 124 City Road, London EC1V 2NX.
The product is designed to turn supported broker exports into transparent UK capital gains calculations. It shows transaction data, disposal-level workings and the share-matching treatment used, so the result can be reviewed before it is used in a tax return.
The founder
Grant Sloane
Founder and director, FiscalFox
“I couldn’t find a tool that worked out my capital gains correctly across more than one broker, so I built one for myself. Then I realised a lot of other investors had the same problem.”Grant on LinkedIn
Grant started FiscalFox in June 2025. Before that he spent eight years building financial products. He was responsible for the Tesco Bank mobile banking app, used by more than 2 million customers, and worked on launching the debit card at the digital bank Nomo. At token.com he led the launch of a centralised crypto exchange in Brazil, covering trading, payments and the custody of customer assets, and went on to become Head of Product. Most recently he led product for tokenised stock and real-world asset execution at Enso.
In all of those roles every balance had to reconcile to the penny. FiscalFox is built to the same standard: each figure in a report traces back to a broker transaction and the HMRC matching rule that was applied to it.
Editorial accountability
Grant Christopher Sloane, the founder and a director of FiscalFox, is accountable for the calculator's published methodology, product-limit disclosures and editorial correction process. His directorship is listed on the public Companies House record.
This attribution identifies who owns the publication process; it is not a claim that FiscalFox or its director provides regulated personal tax advice. Where a user's facts involve unapproved or EMI share options, restricted securities, periods of non-UK residence, remittance, trusts, reorganisations or another specialist issue, the relevant calculation should be checked by a suitably qualified tax adviser.
Our tax-content standard
Tax guides are checked against current GOV.UK pages, HMRC Self Assessment helpsheets and the HMRC Capital Gains Manual. Each dated guide displays when it was last updated and links to the relevant official material. We update rate, allowance and filing content when published rules change, and avoid presenting an estimate as an HMRC submission or personal tax advice.
- Primary sources are preferred over summaries from third-party publishers.
- Worked examples state their assumptions and do not substitute for a user's full facts.
- Material product limitations and transactions requiring manual review are disclosed.
- Calculation outputs retain the underlying matching workings for review.
Editorial checks and calculation-engine tests serve different purposes. The editorial process confirms that published rates, allowances, filing boundaries and linked guidance reflect the cited primary source. Automated tests check deterministic importer and matching behaviour. Neither process can establish that a user's broker history is complete, so warnings and reconciliation steps remain part of the output.
We also run HMRC's own published worked examples through the calculation engine as automated tests. See HMRC's worked examples, reproduced, with HMRC's answers next to ours.
What FiscalFox does and does not do
FiscalFox applies supported UK share-matching logic and prepares calculation reports that can support the SA108 Capital Gains summary. It does not file a return with HMRC, guarantee that an incomplete broker export is complete, or provide regulated personal tax advice. RSU vests and ESPP purchases from supported Schwab and Morgan Stanley exports are handled automatically. Corporate actions, unapproved or EMI share options, restricted securities, unidentified instruments, periods of non-UK residence and remittance circumstances may need additional evidence and professional review.
Corrections and questions
If you spot a source that has changed or believe a guide needs clarification, contact the FiscalFox support team through the support page. We review corrections against primary evidence and update the affected page where appropriate.