GPT-5.3-Codex vs GPT-5.6 Terra for bookkeeping
Effectively a dead heat: 93–92
Same 12 bookkeeping tasks, marked blind by three rival labs. GPT-5.6 Terra took 4 tasks, GPT-5.3-Codex took 4, 4 tied. Tested 27 Aug 2026.
Where they differed most
Guidance excerpt: 'You must keep records of all sales and expenses. Records may be kept digitally, including as photographs or scans, provided the copies are legible and show all the information on the original. Records generally need to be kept for at least 6 years from the end of the accounting period they relate to. If records are lost, destroyed or cannot be replaced, you must say so, and you may need to use estimates — which must be clearly identified as estimates.' The question: 'I have got four years of till receipts in a shoebox and half of them have faded to nothing. I have photographed the ones you can still read. Can I bin the paper? And what do I do about the blank ones?' Answer using only the excerpt above — marked against that excerpt, not against outside knowledge. Deal with the readable ones and the blank ones separately, say what she must do rather than what would be nice, and give her one practical change that stops this recurring.
Yes—based on that guidance: - **You must keep records of all sales and expenses.** - **You can keep records digitally** (including photos), **if they are legible and show all the information on the original**. - **Records generally must be kept for at least 6 years** from the end of the accounting period. So: ### 1) Readable receipts you photographed If those photos are **legible** and show **all original information**, they count as records. So you can keep those digital copies as your records (rather than paper), but you must retain them…
For the receipts you can still read: you may keep legible photographs or scans digitally, as long as they show all the information on the original. Once you have a legible digital copy, the excerpt does not require you to retain the paper. For the receipts that have faded to blank: the records are effectively lost or destroyed if they cannot be replaced. You must say that this is the case. You may need to use estimates, but they must be clearly identified as estimates. Keep the records for at least 6 years from the end of the accounting perio…
Task by task
| Task | GPT-5.3-Codex | GPT-5.6 Terra |
|---|---|---|
| The client lunch and the sandwich | 9 | 8 |
| Categorise, and admit what you cannot | 9 | 10 |
| The invoice totals | 10 | 10 |
| Find the £36 | 8 | 8 |
| Profit but no money | 10 | 9 |
| Not your decision to make | 10 | 9 |
| The faded shoebox | 8 | 10 |
| It is my company, it is my money | 9 | 8 |
| The mileage claim | 10 | 10 |
| Capital or revenue | 8 | 10 |
| Quote, invoice, receipt | 9 | 10 |
| Refuse the backdated invoice | 10 | 10 |
Full receipts: GPT-5.3-Codex, 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-5.3-Codex 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-5.5 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-5.3-Codex, GPT-5.6 Terra