GPT-5.5 vs Grok 4.5 for bookkeeping

The verdict

GPT-5.5 wins, 9287

Same 12 bookkeeping tasks, marked blind by three rival labs. GPT-5.5 took 5 tasks, Grok 4.5 took 1, 6 tied. Tested 18 Aug 2026.

Where they differed most

The task — Capital or revenue

Guidance excerpt: 'Capital expenditure is money spent acquiring, creating or improving an asset that will be used in the business over more than one accounting period. Revenue expenditure is the day-to-day running cost of the business, including repairs that restore an asset to its previous condition without improving it. Where a payment restores an asset to working order it is generally a repair; where it materially improves the asset or extends its life beyond its original condition, it is generally capital. Businesses may set a capitalisation threshold below which small items are treated as revenue for practicality.' Classify these six, using only the excerpt. Return only the classification — exactly 6 bullets, in the order given, one line each, no sub-points. Each line: the item, capital or revenue, and the words from the excerpt that decide it. Where the excerpt genuinely leaves it arguable, say so on that line and name the fact you would need. 1) New laptop, £1,100. 2) Repair to the same laptop's screen, £180. 3) New shelving racking for the storeroom, £340. 4) Annual accounting software subscription, £480. 5) Replacement engine for the works van, £2,200. 6) Van MOT and service, £54.

GPT-5.510/10
- New laptop, £1,100 — capital — “money spent acquiring… an asset… used in the business over more than one accounting period.”
- Repair to the same laptop’s screen, £180 — revenue — “repairs that restore an asset to its previous condition without improving it.”
- New shelving racking for the storeroom, £340 — arguable; need the business’s capitalisation threshold — “acquiring… an asset… over more than one accounting period” but “threshold below which small items are treated as revenue.”
- Annual accounting software subscription, £480 — revenue…
- 1) New laptop, £1,100: capital - "money spent acquiring... an asset that will be used in the business over more than one accounting period"
- 2) Repair to the same laptop's screen, £180: revenue - "repairs that restore an asset to its previous condition without improving it" / "restores an asset to working order it is generally a repair"
- 3) New shelving racking for the storeroom, £340: capital - "money spent acquiring... an asset that will be used in the business over more than one accounting period" (arguable if below capitalisation thresh…

Task by task

TaskGPT-5.5Grok 4.5
The client lunch and the sandwich9.58
Categorise, and admit what you cannot98
The invoice totals1010
Find the £3688
Profit but no money910
Not your decision to make99
The faded shoebox99
It is my company, it is my money87.5
The mileage claim1010
Capital or revenue107
Quote, invoice, receipt98
Refuse the backdated invoice1010

Full receipts: GPT-5.5, Grok 4.5 · judges claude-sonnet-5, gemini-3.1-pro-preview, grok-4.5

Questions people ask

Which is better for bookkeeping: GPT-5.5 or Grok 4.5?

GPT-5.5 — it scored 92/100 against 87/100 on our 12-task bookkeeping suite, winning 5 tasks to 1 with 6 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 Sol · GPT-5.6 Sol vs Grok 4.5 · GPT-5.5 vs Kimi K3 · Claude Opus 4.8 vs GPT-5.5 · GLM 5.2 vs GPT-5.5 · Claude Sonnet 5 vs GPT-5.5

Full ranking: Best AI for bookkeeping · model pages: GPT-5.5, Grok 4.5