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CrestCast · crestcast.co.uk

Due-diligence sheet for financial advisers

Last reviewed 26/09/2026. Questions: hello@crestcast.co.uk

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What CrestCast is

  • A web app that forecasts a UK household’s cashflow, net worth and debt up to ten years ahead, day by day, month by month or year by year.
  • It works from the figures the household enters. A statement CSV the user downloads from their bank can be read on their device to suggest recurring bills and income; the statement itself is not uploaded.
  • UK tax built in: income tax including the Scottish bands, National Insurance, and student loan plans 1, 2, 4, 5 and Postgrad.
  • For couples, each partner’s own money and the joint items, added up into one household view.

Scope

  • CrestCast is a forecasting and planning tool, not regulated financial advice. Nothing in it is financial, tax, investment or legal advice.
  • It makes no recommendations and does not recommend any product or provider.
  • It does not hold, move or invest money.

Who runs it

  • Built by Luke Walsh ACA, a member of Chartered Accountants Ireland, in Belfast, and run by CrestCast Ltd (company number NI744565, registered in Northern Ireland, registered office 2 Grahamsbridge Park, Dundonald, Belfast, Northern Ireland, BT16 2DE).
  • Data controller: CrestCast Ltd, of 2 Grahamsbridge Park, Dundonald, Belfast, Northern Ireland, BT16 2DE.
  • Contact, including data requests: hello@crestcast.co.uk

Data location and security

  • Client figures are stored in a Postgres database run by Supabase in the EU, in Frankfurt (AWS eu-central-1).
  • Each account’s data is private to that user, enforced by row-level security in the database, unless they choose to share it with a partner or an adviser.
  • Encrypted in transit (TLS) and at rest (AES-256) by the database provider.
  • Two-step sign-in with an authenticator app, and passkey sign-in (fingerprint, face or device PIN) in browsers that support it.
  • With two-step sign-in on, deleting the account asks for the second factor again, enforced by the database, and exporting data asks for it in the app.
  • A change history records every change to a user’s figures: what changed, from what to what, when and by whom. The user can read it in the app and export it.
  • A user can export their data from Settings: a full backup file, their dated payments as CSV, and the forecast as a spreadsheet.
  • A user can delete their account from Settings. Nothing is destroyed for 30 days, and cancelling in that time restores it; after that it is deleted permanently.
  • Client data is never sold and never used for advertising.

Sub-processors

  • Supabase: database and sign-in, EU region.
  • Vercel: hosting for the website and the web app, and cookieless analytics. Client figures are not stored there.
  • Stripe: subscription billing.
  • Resend: email delivery.
  • Anthropic: the optional AI assistant, only when a user sends it a message. Not used to train models; can be processed in the United States; CrestCast keeps no copy of the conversation.
  • Google: Google Analytics, only if the visitor accepts it.

Adviser access: view only by default

  • The client invites the adviser by email from Settings > Share with an adviser. An invitation lasts 7 days.
  • The adviser accepts while signed in to a CrestCast account with that email address.
  • The adviser sees the client’s own figures and forecast. They do not see anything the client’s partner entered, the client’s saved versions, past forecast copies or change history.
  • By default the adviser can only view: the database lets them read and refuses every write.
  • The client can switch on Can edit for a named adviser, with their second sign-in step if they use one. The adviser can then change no more than the client can, each change is recorded in the client’s change history under the adviser’s email, and switching it off refuses their next change.
  • Exports are refused in the app while an adviser is viewing a client.
  • The client can stop sharing at any time, with immediate effect. Deleting either account deletes the access.
  • Each invitation, acceptance, viewing and ending is recorded in the client’s change history.

Calculations

  • The tax and benefit rates the app uses are checked against gov.uk on a schedule. A difference is raised for review and approved by hand, never applied automatically.
  • An automated test standard checks the forecast against figures worked out separately from it.
  • A calculation audit on 25/09/2026 checked the arithmetic against hand-worked figures. Its most serious findings are fixed, each with its own test.

Pricing

  • For a client: 30 days free, no card. Then £7.99 a month or £79.99 a year for the whole household.
  • For an adviser: a free account, on request. Viewing a forecast a client has shared needs no subscription.