deepseek-flash costs about $9-$18 a month on an agent workload where Claude Opus 5.5 costs $296, a 16 to 32 times gap.
On vendor-reported benchmarks Claude Opus 5.5 leads on the hardest agentic coding tasks, while the gap is smaller on bounded tasks.
Break-even rule: if Flash is 16 times cheaper, it only needs to succeed once in 16 attempts, provided you can detect failures automatically.
DeepSeek works inside Claude Code through its Anthropic-compatible endpoint, so a hybrid setup is practical.
Check data residency before sending customer data to DeepSeek, and expect safeguards on Claude for biology and cybersecurity work.