The base model for the four paid plans is Claude Opus 5.5

Anthropic has designated Claude Opus 5.5 as the default model across its four paid tiers—Pro, Max, Ultra, and Team—according to a knowledge-work guide published on the 12th. The company recommends the model for everyday research, analysis, writing, and the production of memos, reports, spreadsheets, and presentations, positioning it as suited to most knowledge tasks requiring judgment. The guide did not specify an effective date for the default change or name the default model for the free tier. The shift matters because it pushes Anthropic's flagship model into the baseline experience for paying subscribers, raising the stakes for rivals' paid-tier defaults. What to watch next is confirmation of when the change takes effect and which model anchors the free tier.