The Practice P&L Diagnostic.

An Excel Calculator that runs three consecutive years of a UK general practice P&L through an anomaly-detection framework, surfacing the line items, ratios, and year-on-year movements that warrant a question. Built for partnership-candidate diligence, partner-board financial review, and practice-manager handover.

What this Calculator is for.

Most P&Ls look fine on first read. The lines that matter — the ones a competent reader would ask about — are usually obvious only on comparison: a line whose ratio to revenue has drifted year-on-year, a cost that's grown faster than the funding base it should track, a one-off entry that recurs across multiple years in slightly different forms. Finding these by eye, on three years of figures, is harder than it sounds. The Diagnostic does it systematically.

The user enters three years of the practice's P&L. The Calculator runs the figures through a structured anomaly framework — year-on-year movement, ratio drift, line-level outliers, sub-category benchmarks — and produces a flagged report identifying which lines are worth asking about, and what the question should be.

What's inside.

Seven sheets in a single Excel file, plus an accompanying PDF user guide.

1. Inputs — three years of the practice's P&L, as it appears in the accounts
2. Normalisation — accounting-line standardisation so anomaly detection works across formats
3. Ratios — the key ratios the Diagnostic monitors, year by year
4. Flags — anomalies surfaced by category, with severity indicators
5. Questions — the specific questions to ask, against each flag
6. Summary — a one-page output for board or accountant discussion
7. Methodology — what the Diagnostic does, what it doesn't do, and where its detection thresholds are documented

How it flags.

Conditional formatting makes the output legible at a glance: amber flags indicate movements outside the normal range that may warrant a question; red flags indicate anomalies materially outside the expected pattern that almost certainly warrant one. The framework is not a verdict — flags are prompts for further investigation, not findings of wrongdoing. The PDF user guide explains the threshold framework and how to read the output without over-interpreting it.

"An anomaly is not evidence of a problem. It is evidence that the figure has moved further than the figure normally moves, which is a different and more useful thing. Most flagged lines, on investigation, turn out to have legitimate explanations. The point of the Diagnostic is not to catch the practice doing something wrong — it is to make sure you have asked about every line where the question deserves to be asked."

— from the PDF user guide, Reading the flags

Who it's for.

• Partnership candidates in diligence. Three years of accounts is what you'll be shown. The Diagnostic turns those three years into a structured set of questions you can put to the practice.
• Partner boards on annual review. Running your own three-year P&L through the Diagnostic surfaces the lines your partnership should actually discuss in the year-end review.
• Practice managers in handover. If you've just arrived in post, three years of historical accounts are the fastest route into the practice's commercial reality. The Diagnostic accelerates that path.

What this Calculator is not.

It is a tool, not regulated advice or audit. It does not certify accounts, identify fraud, or replace your accountant's work. The framework is built for UK NHS general practice specifically; it does not produce meaningful flags on private medical practice accounts (use a different framework, in production) or hospital or trust accounts.

What's related.

• Reading a GP P&L Without Flinching — the Guide that teaches how to read the kind of P&L this Diagnostic analyses. £39.
• The Practice P&L Sensitivity Tool — forward-models the same kind of practice. The Diagnostic looks backwards; the Sensitivity Tool looks forwards. £89.