CONFRAG: Confidence-Guided Retrieval-Augmented Generation

Yin Huang, Yifan Ethan Xu, Kai Sun, Vera Yan, Alicia Yi Sun, Haidar Khan, Jimmy Nguyen, Jingxiang Chen, Mohammad Kachuee, Zhaojiang Lin, Yue Liu, Aaron Colak, Anuj Kumar, Wen-tau Yih, Xin Luna Dong


Abstract
Production Retrieval-Augmented Generation (RAG) pays retrieval latency and serving cost on every query – even when the model already knows the answer. We present CONFRAG, a confidence-guided strategy that invokes RAG only when a large language model (LLM) is unlikely to be correct, cutting external retrievals by 5-39% and tail latency by up to 800ms (P90) in a real RAG system while matching the answer quality of always-on RAG. CONFRAG is enabled by CONFQA, a lightweight fine-tuning strategy (one epoch over 3K knowledge-graph facts) that teaches an LLM to answer only when confident and otherwise say "I am unsure", cutting hallucination rates from 20-40% to 5% or below across multiple factuality benchmarks. Two choices make it work in practice: a dampening prompt that discourages overconfident hallucinations, and training on atomic facts that generalizes confidence calibration to unseen domains and question types. At serving time, LLM-QA and RAG run in parallel with early-stopping, so confident answers return immediately.
Anthology ID:
2026.emnlp-industry.171
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing: Industry Track
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Pepa Atanasova, Gholamreza Haffari, Minghan Wang
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
2905–2923
Language:
URL:
https://aclanthology.org/2026.emnlp-industry.171/
DOI:
Bibkey:
Cite (ACL):
Yin Huang, Yifan Ethan Xu, Kai Sun, Vera Yan, Alicia Yi Sun, Haidar Khan, Jimmy Nguyen, Jingxiang Chen, Mohammad Kachuee, Zhaojiang Lin, Yue Liu, Aaron Colak, Anuj Kumar, Wen-tau Yih, and Xin Luna Dong. 2026. CONFRAG: Confidence-Guided Retrieval-Augmented Generation. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing: Industry Track, pages 2905–2923, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
CONFRAG: Confidence-Guided Retrieval-Augmented Generation (Huang et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-industry.171.pdf