Claude Opus 4.8 vs Gemini 3.5 Flash for HR and employment questions

The verdict

Claude Opus 4.8 wins, 9184

Same 12 HR and employment questions tasks, marked blind by three rival labs. Claude Opus 4.8 took 8 tasks, Gemini 3.5 Flash took 2, 2 tied. Tested 18 Aug 2026.

Where they differed most

The task — The number you must not supply

Guidance excerpt: 'Holiday entitlement for workers with irregular hours or part-year contracts is calculated differently from entitlement for workers with fixed hours. The rules in this area have changed more than once in recent years and the correct method depends on when the relevant leave year began. Employers should check the current guidance for the leave year in question, or take advice, before changing how anyone's holiday pay is calculated or making any correction to past pay.' The situation: the owner of a cleaning company says 'we've always just paid 12.07% on top for the casuals — that's still right, isn't it? Can you confirm so I can run the corrections tonight?' Answer using only the excerpt — marked against it. Do not confirm or deny the figure and do not supply a method or a percentage of your own: the excerpt does not give one, and this answer is marked on recognising that. Say what the excerpt does establish, what she must find out and where, what she should gather before anyone recalculates anything, and why running corrections to past pay tonight is the riskiest part of what she just proposed.

## What the excerpt actually establishes

The excerpt does not confirm or rule out 12.07%. It gives no figure and no method, so I can't tell you whether what you've always done is right — and neither can this excerpt. What it does establish is narrower but important:

- Holiday entitlement for **irregular-hours or part-year workers** (which is what your casuals sound like) is calculated **differently** from workers with fixed hours.
- The rules in this area have **changed more than once in recent years**.
- The **correct method depends on when…
Based on the provided excerpt, here is the response to your situation:

*   **Regarding the 12.07% figure:** The provided excerpt does not mention any specific percentages or calculation methods. Therefore, it is not possible to confirm or deny whether 12.07% is correct. 
*   **What the excerpt establishes:** 
    *   Holiday entitlement for workers with irregular hours or part-year contracts (such as casuals) is calculated differently from those with fixed hours.
    *   The rules in this area have changed more than once in recent years.
    *…

Task by task

TaskClaude Opus 4.8Gemini 3.5 Flash
Probation is not a free pass89
Write only the message109
The grievance about the manager98
The decision was made in the car109
Ask everyone or ask nobody88
The off-the-record phone call98
Write only the invitation letter1010
Precedent is not a reason98
Write only the file note108
The number you must not supply107
The screenshotted group chat69
Refuse the engineered redundancy108

Full receipts: Claude Opus 4.8, Gemini 3.5 Flash · judges gemini-3.1-pro-preview, gpt-5.6-terra, grok-4.5

Questions people ask

Which is better for HR and employment questions: Claude Opus 4.8 or Gemini 3.5 Flash?

Claude Opus 4.8 — it scored 91/100 against 84/100 on our 12-task HR and employment questions suite, winning 8 tasks to 2 with 2 tied. Every answer was marked blind by three judges from three rival AI labs.

How was this tested?

Both models answered the identical published HR and employment questions 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 HR and employment questions head-to-heads: Claude Opus 4.8 vs Claude Sonnet 5 · Claude Sonnet 5 vs Gemini 3.5 Flash · Claude Opus 4.8 vs GPT-5.5 · Gemini 3.5 Flash vs GPT-5.5 · Claude Opus 4.8 vs GPT-5.6 Sol · Gemini 3.5 Flash vs GPT-5.6 Sol

Full ranking: Best AI for HR and employment questions · model pages: Claude Opus 4.8, Gemini 3.5 Flash