Prompt-Level Distillation: A Non-Parametric Alternative to Model Fine-Tuning for Efficient Reasoning

Sanket Badhe, Deep Shah


Abstract
Advanced reasoning typically requires Chain-of-Thought prompting, which is accurate but incurs prohibitive latency and substantial test-time inference costs. The standard alternative, fine-tuning smaller models, often sacrifices interpretability while introducing significant resource and operational overhead. To address these limitations, we introduce Prompt-Level Distillation (PLD). We extract explicit reasoning patterns from a Teacher model and organize them into a structured list of expressive instructions for the Student model’s System Prompt. Evaluated using Gemma-3 4B, PLD improved Macro F1 scores on StereoSet (57% to 90.0%) and Contract-NLI (67% to 83%), while increasing LogiQA accuracy to 70%. Similar results on Mistral Small 3.1 demonstrate cross-architecture generalizability, enabling these compact models to match frontier performance with negligible latency overhead. These expressive instructions render the decision-making process transparent, allowing for full human verification of logic, making this approach ideal for regulated industries such as law, finance, and content moderation, as well as high-volume use cases and edge devices.
Anthology ID:
2026.acl-industry.142
Volume:
Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (ACL 2026)
Month:
July
Year:
2026
Address:
San Diego, California, USA
Editors:
Yunyao Li, Georg Rehm, Mei Tu
Venue:
ACL
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Publisher:
Association for Computational Linguistics
Note:
Pages:
2131–2147
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URL:
https://preview.aclanthology.org/ingest-acl/2026.acl-industry.142/
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Cite (ACL):
Sanket Badhe and Deep Shah. 2026. Prompt-Level Distillation: A Non-Parametric Alternative to Model Fine-Tuning for Efficient Reasoning. In Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (ACL 2026), pages 2131–2147, San Diego, California, USA. Association for Computational Linguistics.
Cite (Informal):
Prompt-Level Distillation: A Non-Parametric Alternative to Model Fine-Tuning for Efficient Reasoning (Badhe & Shah, ACL 2026)
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https://preview.aclanthology.org/ingest-acl/2026.acl-industry.142.pdf