For UK accountancy firms
The brown envelope, decoded.
A client photographs the letter, panics, and emails you. Before you open the thread, Envelope has classified it against a registry of letter types, computed the statutory deadline with date rules, and drafted the reply for your review. The dread is optional now.
HMRC · Notice to deliver a Company Tax Return · CT603
CT603 notice · registry match
Filing due 12 months after the end of the period, computed by date rules
Client explanation and response ready for review
The letter problem
The fifteen minutes every letter steals
A brown envelope lands on a client's doormat and your afternoon reroutes. They photograph it, panic, and email you. You translate the officialese, work out which deadline just started ticking, and draft a reply that calms everyone down. Fifteen minutes, multiplied by every letter HMRC and Companies House can print.
Envelope reads the letter and says what it actually means, in words a client can take in without their pulse rising.
It computes the statutory deadline the letter triggers, by date rules, so the countdown starts from arithmetic rather than a skim of paragraph four.
It drafts the client explanation and the response, so the first thing you do with the thread is review, not write.
All three done before you open the email.
Deterministic where it matters
The parts that must be right are not left to the model
Envelope is an AI product with a firm rule about where the AI stops.
Classification runs against a deterministic registry of letter types: SA penalties, compliance checks, VAT assessments, CT603s, strike-off warnings, notices of enforcement, MTD correspondence and more.
Statutory deadlines are computed by pure date arithmetic from the letter's facts. A CT603 due date is a calculation, not an opinion, and the model is never asked for one.
Follow-up questions meet the same standard as the rest of the suite: Athena answers from a curated GOV.UK and legislation.gov.uk corpus, cited, or she refuses rather than guesses.
Nothing sends itself
Drafted for review, not sent
Explanations, appeals and responses arrive as drafts, plainly labelled as drafts. A professional signs everything before it goes anywhere, because the reply to a compliance check is your name on the line, not the software's. Underneath, owner, accountant and viewer roles decide who can do what, and an audit log records who did it. Envelope makes the first draft; the judgement stays yours.
What you get
Built for the firm the letters land on
A registry, not a hunch
Letters are classified against a deterministic registry of HMRC and Companies House letter types. A match is a match, and an unmatched letter says so.
Deadlines by arithmetic
Statutory deadlines are computed by date rules from the letter's own facts. The model explains the letter; it never touches the countdown.
Drafts on arrival
Client explanation, appeal and response drafted before you open the thread. Your first act is review, not a blank page.
Evidence-gated follow-ups
Ask what the letter means for the client and Athena answers strictly from a curated GOV.UK and legislation.gov.uk corpus, cited, or she refuses.
Roles that mean something
Owner, accountant and viewer roles per firm, so the trainee can read the decode without being able to touch the draft that goes out under your name.
Encrypted, logged, exportable
Field-level encryption on sensitive data, an audit log under every action, and GDPR export and delete built in rather than bolted on.
Pricing
On the page, like it should be
Solo is £99 a month for 100 letters and 3 users. Practice is £199 for 400 letters and 10 users. Both +VAT, monthly, cancel anytime. Envelope is in early access: built, working, and onboarding firms directly rather than through a signup page. Email us and we will set you up.
Early access. Ask for a seat
Part of the suite
The letter is never the whole job
A brown envelope rarely arrives alone. It usually triggers a question, which Footnote answers with citations; a conversation about fees, which Engage turns into a repriced engagement; or a deadline someone has to track, which AccountFlow carries across the whole practice. Same evidence gate everywhere.
Questions
Asked before you ask
Which letter types does Envelope recognise?
The registry covers SA penalties, compliance checks, VAT assessments, CT603s, strike-off warnings, notices of enforcement, MTD correspondence and more. Classification runs against that registry, not against a guess. A letter that does not match is flagged as unrecognised rather than shoehorned into the nearest type.
How are the deadlines computed?
By pure date rules. Each registered letter type carries its statutory timing, and Envelope applies it as arithmetic to the dates on the letter. A CT603 filing deadline is 12 months after the end of the accounting period, so that is what gets computed. The model never produces a date.
Does Envelope send anything automatically?
No. Explanations, appeals and responses arrive as drafts, and a professional signs everything before it leaves the building. There is no send button pointed at HMRC, and there never will be.
What happens to the letters and client data?
Each firm sits in its own tenant with owner, accountant and viewer roles. Sensitive fields are encrypted at the field level, every action is written to an audit log, and you can export or delete a client's data on request. That is GDPR compliance in practice, not just in the privacy policy.
How does early access work?
Envelope is built but not yet publicly deployed, so there is no signup page to click through. Email us, we onboard your firm directly, and you pay the price on this page: Solo £99 or Practice £199 a month, +VAT, monthly, cancel anytime.
Twenty seconds of it
Watch a letter get decoded
The letter lands, the registry matches it, the deadline is computed by date rules, and the draft reply waits for your review. The whole product in one loop.
The next brown envelope is already in the post
Email us and we will onboard your firm directly. 100 or 400 letters a month, classified, dated and drafted before you open the thread.