GPT-5.5 vs GPT-5.6 Terra for bookkeeping

The verdict

Effectively a dead heat: 9392

Same 12 bookkeeping tasks, marked blind by three rival labs. GPT-5.6 Terra took 3 tasks, GPT-5.5 took 1, 8 tied. Tested 18 Aug 2026.

Where they differed most

The task — The client lunch and the sandwich

Guidance excerpt: 'VAT incurred on business entertainment provided to people who are not employees cannot normally be reclaimed as input tax. VAT on subsistence — reasonable meals and drinks for employees, or for the business owner, while travelling on business — can normally be reclaimed if you hold a valid VAT invoice. Where one bill covers both employees and non-employees, only the employee element may be reclaimed. A card receipt that does not show the supplier VAT number is not a valid VAT invoice.' The situation: Ray runs a VAT-registered building firm. In March he has two receipts. One is £86.40 for lunch with a prospective client, at which he also ate; it is a card slip with no VAT number on it. The other is £14.20 for his own sandwich and coffee at a motorway services on the way to a site 90 miles away, with a full VAT receipt. Answer using only the excerpt above — your answer is marked against that excerpt, not against outside knowledge. Take each receipt in turn, say what happens to the VAT and to the cost itself in the books, and say plainly which point here is one to put to his accountant rather than settle from the excerpt.

GPT-5.59.5/10
Using only the excerpt:

### 1) £86.40 lunch with prospective client, Ray also ate — card slip, no VAT number

- **VAT:** Do **not** reclaim any VAT.  
  Reasons from the excerpt:
  - It is business entertainment for a **non-employee** prospective client, and VAT on that cannot normally be reclaimed.
  - The card slip has **no supplier VAT number**, so it is **not a valid VAT invoice** anyway.
- **Cost in the books:** Enter the **full £86.40 gross cost** as a cost, with **no input VAT split out/reclaimed**. It would naturally be recorded as cli…
1. **£86.40 lunch with prospective client (card slip, no VAT number)**  
   - **VAT:** Do not reclaim any VAT. This is business entertainment involving a non-employee, and the card slip is not a valid VAT invoice because it has no supplier VAT number.  
   - **Cost in the books:** Record the full £86.40 as the gross cost, with no input VAT recovery.  
   - **Accountant point:** The excerpt does not say whether the entertainment cost itself is allowable for tax or exactly how it should be categorised in the accounts. That is the point to put to…

Task by task

TaskGPT-5.5GPT-5.6 Terra
The client lunch and the sandwich9.58
Categorise, and admit what you cannot910
The invoice totals1010
Find the £3688
Profit but no money99
Not your decision to make99
The faded shoebox910
It is my company, it is my money88
The mileage claim1010
Capital or revenue1010
Quote, invoice, receipt910
Refuse the backdated invoice1010

Full receipts: GPT-5.5, GPT-5.6 Terra · judges claude-sonnet-5, gemini-3.1-pro-preview, grok-4.5

Questions people ask

Which is better for bookkeeping: GPT-5.5 or GPT-5.6 Terra?

Effectively a dead heat: GPT-5.6 Terra edged it 93/100 to 92/100 on our bookkeeping suite — too close to matter, so pick on price or the product you already use.

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-5.6 Sol vs GPT-5.6 Terra · GPT-5.3-Codex vs GPT-5.6 Terra · Claude Fable 5 vs GPT-5.6 Terra · GPT-5.6 Terra vs Grok 4.5 · GPT-5.6 Terra vs Qwen3.7 Max · GPT-5.6 Terra vs Kimi K3

Full ranking: Best AI for bookkeeping · model pages: GPT-5.5, GPT-5.6 Terra