Finetune Once: Decoupling General & Domain Learning with Dynamic Anchor Annealing

Yang Tang, Ruijie Liu, Yifan Wang, Shiyu Li, Peiming Li, Zheng Wei


Abstract
Fine-tuning large language models on domain data is a standard practice, yet vanilla pipelines rely on a costly data mixture sweep to avoid catastrophic forgetting of general capabilities. We propose Dynamic Anchor Annealing (DAA), a full-parameter fine-tuning framework that decouples general and domain learning at the gradient level rather than at the data level. DAA estimates a global gradient anchor once on general data through zero learning rate training, anchors the domain gradient toward this anchor during fine-tuning, modulates step sizes by the cosine similarity between the two gradients, and combines this with annealing learning. Under this design, fine-tuning relies solely on domain data and does not lose general capability. Across four domains and three base models, DAA improves the joint domain and general harmonic mean by 12.5 points on average over direct fine-tuning and by 3.8 points over vanilla data mixture fine-tuning, and the margin widens to 66.9 points on a temporal out-of-distribution setting where direct fine-tuning collapses. Our headline 91% reduction in GPU hours is a workflow level saving from removing the mixture ratio sweep rather than a per run speedup, since the per run cost of DAA is comparable to direct fine-tuning.
Anthology ID:
2026.emnlp-main.2532
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:
57590–57607
Language:
URL:
https://aclanthology.org/2026.emnlp-main.2532/
DOI:
Bibkey:
Cite (ACL):
Yang Tang, Ruijie Liu, Yifan Wang, Shiyu Li, Peiming Li, and Zheng Wei. 2026. Finetune Once: Decoupling General & Domain Learning with Dynamic Anchor Annealing. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 57590–57607, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Finetune Once: Decoupling General & Domain Learning with Dynamic Anchor Annealing (Tang et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.2532.pdf