Privacy notice
Last updated 18 October 2026. Plain English, kept short.
Who we are
This site is run by J. Chisholm, a sole trader trading as cissplit, who is responsible for your data. Email: support@cissplit.co.uk.
What we collect
This site doesn't ask for an account or personal details, and doesn't use tracking or advertising cookies. Our hosting provider, Cloudflare, processes basic technical data (such as IP addresses) to deliver and protect the site.
If you email us, we keep your email and our reply so we can help you, and delete them when they're no longer needed. We don't sell or share them.
When you use the tool
What: the CIS statements you upload. They usually show your name, your contractor's details and the amounts you were paid, and may show your UTR. We don't need your UTR or National Insurance number, so black them out first if you like. We only need the figures.
Why: to read it and show you the results, because you asked us to. We don't store your files or the results: they go straight back to your browser, and anything you download is made on your own device.
Who reads it: our AI provider, Anthropic, reads it to pull out what's needed. Under its terms Anthropic may not use it to train its models, and deletes it within 30 days (longer only if it's flagged for breaking its usage policy, or the law requires). Cloudflare, our hosting provider, passes the file through.
Outside the UK: Anthropic may process your file in the US. That transfer is protected by the UK International Data Transfer Addendum to the EU Standard Contractual Clauses, which forms part of Anthropic's data processing terms.
Usage limits: to limit free use, we keep a scrambled (hashed) form of your internet (IP) address for 30 days. We also keep overall counts of uses, with no personal details.
Figures kept in your browser
So you don't lose them if you buy credits partway through, the figures already read are kept in your browser tab (session storage) until you close the tab or press “Start again”. Your files aren't kept, and we never receive this copy.
If you buy credits
Payments are handled by Stripe, which collects your card details (we never see them) and your email address for the receipt. We keep a record of the payment and your credit balance, linked to a random credit key stored in your browser and in your private link. We keep payment records for six years because the law requires it for tax.
Our legal reasons
We read your files and provide credits to carry out our agreement with you. We keep the hashed IP address to keep the free version fair and affordable, and reply to emails, because we have a legitimate interest in doing so; you can object by emailing us. We keep payment records because the law requires it.
Your rights and complaints
You can ask to see, correct or delete your data by emailing support@cissplit.co.uk. To complain about how we handle your data, email us: we'll acknowledge it within 30 days and tell you what we've done. You can also complain to the Information Commissioner's Office.