Claude Opus 4.8 vs Claude Sonnet 5 for property and lettings admin

The verdict

Claude Opus 4.8 wins, 8985

Same 12 property and lettings admin tasks, marked blind by three rival labs. Claude Opus 4.8 took 5 tasks, Claude Sonnet 5 took 2, 5 tied. Tested 18 Aug 2026.

Where they differed most

The task — The nine-year-old carpet

Guidance excerpt: 'Deductions from a tenancy deposit must be reasonable and supported by evidence. A landlord cannot charge for fair wear and tear, which is the reasonable deterioration of the property and its contents through normal use over the length of the tenancy. Adjudicators consider the age, quality and condition of an item at the start of the tenancy and will not normally award the cost of replacing an old item with a new one, since that would place the landlord in a better position than before — an apportionment reflecting the remaining useful life is more usual. The burden of proving a deduction is reasonable rests with the landlord.' The evidence: the living room carpet was 9 years old at check-in. The signed check-in report records it as 'worn throughout, marked in two places near the door'. The check-out photograph shows a large dark stain, roughly 40cm across, in the centre of the room, which was not there at check-in. The landlord has a quote of £340 to replace the carpet and wants the whole £340 from the deposit. The tenant disputes it entirely. Answer using only the excerpt — marked against it. Assess the claim, say what the landlord can realistically expect and why, name what evidence would strengthen and what would sink it, and write the position statement the agent would submit to the scheme adjudicator.

# Assessment Against the Excerpt

## The claim as it stands

The landlord wants the **full £340 replacement cost**. Under the excerpt, this fails on two clear points:

**1. Betterment / age and remaining useful life.** The excerpt states adjudicators "will not normally award the cost of replacing an old item with a new one, since that would place the landlord in a better position than before — an apportionment reflecting the remaining useful life is more usual." The carpet was **9 years old** at check-in. Carpet is a wearing item with a limited…
# Assessment Against the Guidance

## Applying the Excerpt to the Facts

The excerpt establishes several tests that must be applied here:

**1. Is there damage beyond fair wear and tear?**
Yes. The check-in report records the carpet as "worn throughout, marked in two places near the door" — this is the baseline condition, itself already showing wear consistent with a 9-year-old carpet. The check-out photograph shows a new, distinct feature: a large dark stain, roughly 40cm across, in the centre of the room, not present at check-in. A stain of t…

Task by task

TaskClaude Opus 4.8Claude Sonnet 5
Two routes, one worried tenant910
Six weeks late and hoping99
Write only the arrears email1010
The pre-tenancy checklist98
Write only the renewal reply1010
Three repairs, one Tuesday86
The nine-year-old carpet85
The rent rise by text message108
Every claim in the advert must be true98
The compliance data, as JSON1010
What the agent must not promise58
Refuse the lock change1010

Full receipts: Claude Opus 4.8, Claude Sonnet 5 · judges gemini-3.1-pro-preview, gpt-5.6-terra, grok-4.5

Questions people ask

Which is better for property and lettings admin: Claude Opus 4.8 or Claude Sonnet 5?

Claude Opus 4.8 — it scored 89/100 against 85/100 on our 12-task property and lettings admin suite, winning 5 tasks to 2 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 property and lettings admin 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 property and lettings admin head-to-heads: Claude Opus 4.8 vs GPT-5.5 · Claude Sonnet 5 vs GPT-5.5 · Claude Opus 4.8 vs GPT-5.6 Sol · Claude Sonnet 5 vs GPT-5.6 Sol · Claude Opus 4.8 vs Kimi K3 · Claude Sonnet 5 vs Kimi K3

Full ranking: Best AI for property and lettings admin · model pages: Claude Opus 4.8, Claude Sonnet 5