Claude Fable 5 vs GPT-5.5 for bookkeeping
GPT-5.5 wins, 92–89
Same 12 bookkeeping tasks, marked blind by three rival labs. GPT-5.5 took 5 tasks, Claude Fable 5 took 4, 3 tied. Tested 27 Aug 2026.
Where they differed most
Nine lines from a sole trader's business bank feed. She is a self-employed dog groomer. 1) 'AMZN Mktp UK £41.99'. 2) 'PETSMART WHOLESALE £238.00'. 3) 'SHELL BRIGHOUSE £62.10'. 4) 'TRANSFER TO J CROSSLEY £600.00'. 5) 'SAGE UK LTD £22.00'. 6) 'B&Q 1147 £84.55'. 7) 'HMRC NDDS £310.00'. 8) 'COSTA COFFEE £9.40'. 9) 'DVLA VEHICLE TAX £190.00'. Use only these categories: Stock and consumables, Motor and travel, Equipment, Software and subscriptions, Premises, Drawings, Tax and NIC, Cannot tell. Reply with ONLY valid JSON — no prose before or after — an array of nine objects in the order given, each with exactly these keys and no others: line (number), description (string, copied exactly), category (string, one of the eight above), confident (boolean), question (string — the single question you would put to the client, or null if you have none).
```json
[
{
"line": 1,
"description": "AMZN Mktp UK £41.99",
"category": "Cannot tell",
"confident": false,
"question": "What did you buy from Amazon — was it grooming supplies, equipment, or something personal?"
},
{
"line": 2,
"description": "PETSMART WHOLESALE £238.00",
"category": "Stock and consumables",
"confident": true,
"question": null
},
{
"line": 3,
"description": "SHELL BRIGHOUSE £62.10",
"category": "Motor and travel",
"confident": true,
"question": "Roughly what…[
{
"line": 1,
"description": "AMZN Mktp UK £41.99",
"category": "Cannot tell",
"confident": false,
"question": "What was bought from Amazon, and was it wholly for the dog grooming business?"
},
{
"line": 2,
"description": "PETSMART WHOLESALE £238.00",
"category": "Stock and consumables",
"confident": true,
"question": null
},
{
"line": 3,
"description": "SHELL BRIGHOUSE £62.10",
"category": "Motor and travel",
"confident": false,
"question": "Was this fuel for business trave…Task by task
| Task | Claude Fable 5 | GPT-5.5 |
|---|---|---|
| The client lunch and the sandwich | 8 | 9.5 |
| Categorise, and admit what you cannot | 5 | 9 |
| The invoice totals | 10 | 10 |
| Find the £36 | 10 | 8 |
| Profit but no money | 9 | 9 |
| Not your decision to make | 10 | 9 |
| The faded shoebox | 9 | 9 |
| It is my company, it is my money | 9 | 8 |
| The mileage claim | 9 | 10 |
| Capital or revenue | 9 | 10 |
| Quote, invoice, receipt | 10 | 9 |
| Refuse the backdated invoice | 9 | 10 |
Full receipts: Claude Fable 5, GPT-5.5 · judges gemini-3.1-pro-preview, gpt-5.6-terra, grok-4.5
Questions people ask
Which is better for bookkeeping: Claude Fable 5 or GPT-5.5?
GPT-5.5 — it scored 92/100 against 89/100 on our 12-task bookkeeping suite, winning 5 tasks to 4 with 3 tied. Every answer was marked blind by three judges from three rival AI labs.
How was this tested?
Both models answered the identical published bookkeeping tasks. Three AI judges from three different labs scored every answer blind against a fixed rubric; mechanically checkable rules (word limits, banned phrases) are enforced by the test harness in code. The raw outputs and judge verdicts are downloadable.
More bookkeeping head-to-heads: GPT-5.5 vs GPT-5.6 Terra · Claude Fable 5 vs GPT-5.6 Terra · GPT-5.5 vs GPT-5.6 Sol · Claude Fable 5 vs GPT-5.6 Sol · GPT-5.3-Codex vs GPT-5.5 · Claude Fable 5 vs GPT-5.3-Codex
Full ranking: Best AI for bookkeeping · model pages: Claude Fable 5, GPT-5.5