Default Zero-Shot LLM APIs Over-Flag Indian Financial SMS: A Policy-Aligned Benchmark and Template-Level Pre-Deployment Audit

Sachin Gupta


Abstract
Generic ham/spam labels do not define a financial-fraud blocking policy. We present a 1,393-message policy-aligned Indian SMS benchmark in Hindi, Hinglish, and English-India, separating source labels, fraud/non-fraud/unclear adjudication, and allow/review/block actions. GPT-4o and Gemini helped adjudicate source-positive messages, so positive metrics are secondary. Our primary endpoint is false-positive rate (FPR) on 1,294 policy-negatives: 1,222 untouched source negatives plus 72 source positives converted to safe. Under a common minimal prompt, six LLM APIs exceed illustrative 1% FPR gates on Bank and UPI templates. GPT-4o-mini records 77.3% and 56.9% FPR; a fine-tuned 270M XLM-R records 0.0% on both, 0.4% globally, and 0.980 recall. Policy definitions and seven examples reduce GPT-4o to 0.0% Bank/UPI and 1.5% global FPR at 0.949 recall; Claude reaches 1.8% at 0.960 recall. Prompting changes which gate fails. GPT-4o P3 and the AND consensus meet the FPR gates at lower policy-label recall; the local model meets both FPR and recall gates on this benchmark. Because positive labels partly use GPT-4o/Gemini, recall and F1 are secondary, not an overall ranking. We release labels, prompts, parsed decisions, analysis code, and checkpoints without a production or unseen-institution claim.
Anthology ID:
2026.groundlm-1.79
Volume:
Proceedings of the 1st Workshop on Grounding Language Models: Learning Faithfully and Efficiently (GroundLM 2026)
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Yimu Wang, Yee Man Choi, Di Wu, Siqi Ouyang, Mozhgan Nasr Azadani, Yi R. (May) Fung
Venues:
GroundLM | WS
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
1124–1136
Language:
URL:
https://aclanthology.org/2026.groundlm-1.79/
DOI:
Bibkey:
Cite (ACL):
Sachin Gupta. 2026. Default Zero-Shot LLM APIs Over-Flag Indian Financial SMS: A Policy-Aligned Benchmark and Template-Level Pre-Deployment Audit. In Proceedings of the 1st Workshop on Grounding Language Models: Learning Faithfully and Efficiently (GroundLM 2026), pages 1124–1136, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Default Zero-Shot LLM APIs Over-Flag Indian Financial SMS: A Policy-Aligned Benchmark and Template-Level Pre-Deployment Audit (Gupta, GroundLM 2026)
Copy Citation:
PDF:
https://aclanthology.org/2026.groundlm-1.79.pdf
Attachment:
 2026.groundlm-1.79.attachment.zip