BORA-BUDGET: Learning When to Think Under a Token Budget

Zilong Wang, Kang Pan, Xiao Zhang, Erli Meng, Shuai Li


Abstract
Hybrid-thinking language models expose both cheap non-thinking and expensive thinking modes, creating a deployment problem: deciding when additional reasoning is worth its token cost and override risk. We formulate this problem as budgeted opportunity allocation, where a controller first obtains a cheap seed answer, estimates the marginal value and risk of paid thinking, and preserves the seed unless an adoption gate accepts the thinking result. We propose Bora-Budget, a budget-aware inference framework for frozen LLMs, and instantiate it as Bora-Switch-Calibrated. The controller uses seed-state features to predict helpfulness, harmfulness, and thinking cost, then allocates thinking through either frontier operating points or an AutoThreshold policy calibrated to a total token budget. Across LLM scales on math dataset, the method substantially improves over random allocation and approaches uniform-thinking accuracy under lower token budgets. Transfer results on multiple-choice, code, and hard-QA tasks show promising but uneven generalization: trace length remains a strong baseline, harmful overrides are reduced but not eliminated, and learning how much to think remains open. These results position Bora-Budget as a seed-preserving control layer for budgeted inference rather than a replacement for stronger always-thinking baselines.
Anthology ID:
2026.emnlp-main.408
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
9380–9400
Language:
URL:
https://aclanthology.org/2026.emnlp-main.408/
DOI:
Bibkey:
Cite (ACL):
Zilong Wang, Kang Pan, Xiao Zhang, Erli Meng, and Shuai Li. 2026. BORA-BUDGET: Learning When to Think Under a Token Budget. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 9380–9400, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
BORA-BUDGET: Learning When to Think Under a Token Budget (Wang et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.408.pdf