Anthropic halved Sonnet 5.5 cache reads, and its own tool showed the old price for two days
Anthropic halved the price of prompt cache reads on Claude Sonnet 5.5 on October 7, and for the next two days its own coding tool priced them at the old rate. The cut is in Anthropic's platform release notes: "We've lowered the price of prompt cache reads on Claude Sonnet 5.5 from $0.20 USD to $0.10 USD per million tokens: 0.05x the base input price instead of 0.1x. Cache writes and all other prices are unchanged."
The Claude Opus 5.5 launch card, with the model name in white over a photograph of a horizon at dusk. Image: Anthropic
Claude Code caught up on October 9. The changelog entry for version 2.1.296 reads: "Updated /cost, the status line, --max-budget-usd and the SDK's cost figures to price Sonnet 5.5 cache reads at $0.10 per million tokens (was $0.20)." So four places where Claude Code puts a price on a session were each working to a figure Anthropic had stopped charging.
What the cut is worth on a cached prompt
A cache read is what you pay to reuse a prompt prefix you have already stored, and it is the bulk of the token traffic in any agent that keeps reloading the same instructions and the same files. Anthropic's pricing page now lists Claude Sonnet 5.5 at $2 per million input tokens, $2.50 for a five-minute cache write, $4 for a one-hour write, $0.10 for a cache read and $10 per million output tokens. A footnote carries the multiplier: "Cache hits and refreshes on Claude Opus 5.5 and Claude Sonnet 5.5 are priced at 0.05x the base input price."
Every other current Claude model stays on the standard 0.1x, with Claude Fable 5.1 and Claude Mythos 5.1 at 0.025x. Claude Opus 5.5 did not move either: its base input price is $4, so 0.05x of that is the $0.20 per million tokens the page still gives it. One model got cheaper to re-read, and it is the one Anthropic launched in late September at $2 and $10 per million tokens.
Two days of figures at twice the rate
The dates are first-party on both halves. Anthropic dates the price change to October 7 in its release notes. Version 2.1.295 of Claude Code went to the npm registry at 18:22:58 UTC on October 8 without the correction, and 2.1.296 followed at 16:58:10 UTC on October 9 with it. Anywhere in that window, /cost and the status line were reporting cache reads at $0.20 per million tokens against a billed rate of $0.10.
Anthropic does not say that anyone was billed the old rate, and the wording is careful: what changed in 2.1.296 is the cost figures the tool displays. On a cache-heavy session, the displayed figure for those tokens would have been double the rate Anthropic had published.
Why an Anthropic date is not quite a date
One caveat belongs on any figure quoted from these pages. Anthropic edits release-note entries after publishing them, including the text under earlier date headings, so an entry dated October 7 is what the page said at the moment it was read rather than a record of what shipped that day. Everything quoted here was read at 21:33 to 21:35 UTC on October 10, and the npm publication times at 21:52 UTC the same day.
The separate stable release channel is on 2.1.287, published on October 1, and by the changelog's own account any build before 2.1.296 prices Sonnet 5.5 cache reads at the old $0.20. Anthropic has shipped these releases quickly all month, fast enough for 2.1.293 to withdraw a cloud-session fix two days after shipping it. For anyone reading a running total, the version printing it is part of the figure.
