Claude Opus 4.8 vs DeepSeek V4 Pro for bookkeeping

The verdict

Claude Opus 4.8 wins, 8370

Same 12 bookkeeping tasks, marked blind by three rival labs. Claude Opus 4.8 took 7 tasks, DeepSeek V4 Pro took 0, 5 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.

**Receipt 1: £86.40 lunch with prospective client (card slip, no VAT number)**

Two separate problems block any VAT reclaim here.

First, the entertainment point. The lunch is with a prospective client — a person who is not an employee. Under the excerpt, VAT on business entertainment provided to non-employees cannot normally be reclaimed as input tax. Ray also ate at this lunch, so in principle one bill covers both an employee/owner element and a non-employee element, and only the employee element could be reclaimed. But —

Second, the invoice…
**Receipt 1: £86.40 lunch with a prospective client (Ray also ate) – card slip, no VAT number**

- **VAT:** No input tax can be reclaimed. The card slip does not show the supplier’s VAT number, so it is not a valid VAT invoice. Additionally, the meal is business entertainment provided to a non-employee, which cannot normally be reclaimed.
- **Cost in the books:** The full £86.40 is treated as a business expense (entertainment). The irrecoverable VAT is simply part of that cost.

**Receipt 2: £14.20 sandwich and coffee at motorway services (trav…

Task by task

TaskClaude Opus 4.8DeepSeek V4 Pro
The client lunch and the sandwich95
Categorise, and admit what you cannot98
The invoice totals1010
Find the £3633
Profit but no money88
Not your decision to make108
The faded shoebox98
It is my company, it is my money97
The mileage claim108
Capital or revenue88
Quote, invoice, receipt96
Refuse the backdated invoice55

Full receipts: Claude Opus 4.8, DeepSeek V4 Pro · judges gemini-3.1-pro-preview, gpt-5.6-terra, grok-4.5

Questions people ask

Which is better for bookkeeping: Claude Opus 4.8 or DeepSeek V4 Pro?

Claude Opus 4.8 — it scored 83/100 against 70/100 on our 12-task bookkeeping suite, winning 7 tasks to 0 with 5 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: Claude Opus 4.8 vs GPT-5.6 Sol · DeepSeek V4 Pro vs GPT-5.6 Sol · Claude Opus 4.8 vs GPT-5.5 · DeepSeek V4 Pro vs GPT-5.5 · Claude Opus 4.8 vs Grok 4.5 · DeepSeek V4 Pro vs Grok 4.5

Full ranking: Best AI for bookkeeping · model pages: Claude Opus 4.8, DeepSeek V4 Pro