AI21 and Deel post-train Nemotron 3.5 Super VL to outperform Claude Opus 5.5 on global payroll at 50x lower cost

·2026.11.04 09:00

Key point

A three-week engagement used near-policy SFT and SDPO to lift the model's quality by 20.7 points over the base and 8 points over the frontier competitor.

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Details

  • AI21 and Deel post-trained NVIDIA Nemotron 3.5 Super VL to surpass Claude Opus 5.5 by 8 points on quality for global payroll while costing 50x less per 1M tokens.
  • The model achieved a 20.7-point quality improvement over the base model, reaching 0.720 criteria met and 0.339 all criteria met on the dev set.
  • Training used a sequential approach: near-policy SFT on 412 curated examples followed by SDPO (self-distillation policy optimization) on 698 questions.
  • Near-policy SFT lifted performance from 0.513 to 0.657 criteria met by training on the model's own hint-guided rollouts to avoid catastrophic forgetting.
  • SDPO improved results to 0.720 criteria met by using a privileged teacher to score the student's tokens, allowing learning from questions the model initially got wrong without requiring gold answers.
  • The base model's primary failure mode was incomplete answers (hedging or missing figures) rather than factual errors, which the post-training process corrected by steering the model to use existing knowledge.

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