Quick answer
Every number on the accounts and on the corporation tax computation is calculated by rules, not produced by a language model. The rules are the Companies Act 2006, CTA 2010 and the reporting standard for the entity, applied line by line, so the same records give the same answer every time and the workings are on the working papers. AI is used only for wording and for suggesting options that you choose from.
What is calculated
The mapping arithmetic, every reconciliation, the capital allowances, marginal relief, the s.455 charge, deferred tax, the audit exemption test, the ratios, the rounding, the statutory deadlines and every figure that reaches a statement or the computation. Each one is reproducible and traceable: the schedule that produced it is in the working papers, and the figure on the face ties to the note behind it.
This is also the contractual position in the terms: figures are produced by deterministic rules, AI drafts and suggestions are always shown to you for review, and no suggestion takes effect without a decision you record.
What the AI is used for
A short and deliberately narrow list:
Narrative for the analytical review, drafted from the variances AllDone has already computed, on demand from the review screen.
A plain-English "what looks off" read and the partner's overall review, both grounded only in signals AllDone raised.
Disclosure note wording, where you want a draft rather than the standard wording.
The client-facing documents: the plain-English report for the business owner, a client email, and the write-up after a meeting from notes you typed.
Suggestions you confirm: which statement line an unmapped account belongs to, which asset class a capitalised cost looks like, and how the columns of a file layout AllDone has not met before should be read.
In every case the figures are already fixed before the model is asked, the draft is editable, and the suggestion is one option on a card you answer. Nothing a model returns becomes a number.
What this means when someone challenges a figure
Open the working papers and follow the schedule. The lead schedule shows the accounts behind the line, the reconciliation shows what it was agreed to, and the decision register shows who decided what and why. There is no step in that chain where the answer came from a model.
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