SpendSight: Privacy-Preserving Personal Finance Q&A with Sub-2B LLMs

Sajag Swami, Yash Pandey


Abstract
People often speculate about their personal finances: *"Has my spending on groceries increased compared to past year?"*, *"How does my spending on clothes look for the past 6 months?"*. However, answering them with cloud-hosted LLMs transmits sensitive financial data to external servers, exposing users to data leakage and inferential privacy risks. We present **SpendSight**, a study of fully on-device personal finance Q A tool calling that keeps all data strictly local. We evaluate seven quantized models (six sub-2B and one 3B) across 115 test cases and five analytical tools, comparing single-agent against dual-agent (router-specialist) architectures. Dual-agent decomposition yields the largest time gains for the Qwen3.5 family. **Qwen3.5-0.8B** achieves **61.7% Correct Ratio** (**89.1% Task Accuracy**) in **3.0 s** with **1.2 GB RAM** in dual-agent mode. A 3B reference model (**G9v3-3B**, Q4_K_M) achieves **71.7% Correct Ratio** (**90.6% Task Accuracy**) at **2.3 s** in single agent mode, suggesting that larger models with aggressive quantization can bypass decomposition.
Anthology ID:
2026.finnlp-1.14
Volume:
Proceedings of the 11th Workshop on Financial Technology and Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Jimin Huang, Yongjae Lee, Sophia Ananiadou, Hsin-Hsi Chen, Hiroya Takamura, Chung-Chi Chen
Venues:
FinNLP | WS
SIG:
SIGFinTech
Publisher:
Association for Computational Linguistics
Note:
Pages:
153–179
Language:
URL:
https://aclanthology.org/2026.finnlp-1.14/
DOI:
Bibkey:
Cite (ACL):
Sajag Swami and Yash Pandey. 2026. SpendSight: Privacy-Preserving Personal Finance Q&A with Sub-2B LLMs. In Proceedings of the 11th Workshop on Financial Technology and Natural Language Processing, pages 153–179, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
SpendSight: Privacy-Preserving Personal Finance Q&A with Sub-2B LLMs (Swami & Pandey, FinNLP 2026)
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PDF:
https://aclanthology.org/2026.finnlp-1.14.pdf