Cookie and Local Storage Policy
Last updated: 23 August 2026
1. What These Technologies Are
Cookies are small values stored by a website or third party. Browser local storage is a similar device-storage mechanism that can persist application settings and session data. UK privacy rules apply to both where they store or access information on your device.
2. Essential Storage
The accounting application uses essential local storage to maintain your Supabase authentication session, remember the active company, keep user-interface preferences, and hold a persistent random device identifier required for HMRC fraud-prevention headers. The authentication token is transmitted to Supabase to authenticate requests; the HMRC device identifier is sent to our secure filing function and HMRC when you use MTD features.
| Storage | Purpose | Typical duration |
|---|---|---|
| sb-…-auth-token | Authenticated Supabase session and refresh token | Until sign-out, expiry, or browser removal |
| my_ltd_company_id | Active tenant selection | Until changed or removed |
| my_ltd_hmrc_device_id | Persistent random identifier required for MTD fraud prevention | Until browser removal |
| cookie-preferences | Remembers whether optional analytics were accepted or rejected | Until browser removal |
3. Optional Analytics
Google Analytics and Vercel Analytics do not load until you select “Accept analytics” in the banner. Google Analytics may then set cookies including _ga and a measurement-specific _ga_… cookie, generally for up to two years, to distinguish visits and sessions. Vercel Analytics receives page-view information after consent and is designed not to use a cross-site visitor cookie.
Rejecting analytics does not affect the accounting service. We do not use advertising storage or enable ad personalisation.
4. Changing Your Choice
You can withdraw or change analytics consent by clearing the cookie-preferences entry in your browser's site data and reloading this website. You can also delete analytics cookies using your browser settings. Clearing essential authentication storage will sign you out.
5. Local-Only Mode and Migration
Some development or demonstration features can temporarily store records locally. If you authenticate and enable backend storage, the application may migrate those records to your company database. Local storage should not be treated as a secure accounting archive or backup.
6. Contact
For questions about cookies or device storage, contact hello@myltdaccounts.co.uk.