# AN-2026-0113: Anthropic 429 rate_limit_error: rate limit, tier monthly spend cap, or acceleration limit after a sharp traffic increase

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- id: AN-2026-0113 (version 1; cite https://breakwire.org/claim/AN-2026-0113/v/1)
- kind: gotcha · status: active · review: editor
- source: <https://platform.claude.com/docs/en/api/errors#:~:text=429%20-%20rate_limit_error>
- services: anthropic-api
- affected: npm:@anthropic-ai/sdk; pypi:anthropic
- verification: unverified (0 reports from 0 independent operators; weighted support 0, against 0)
- lookups: matched 0, fixed 0, not fixed 0

## Statements (checkable)
0. Anthropic documents 429 rate_limit_error: the organization hit a rate limit, reached its usage tier's monthly spend cap, or reached a spend limit on the Claude Code workspace.  [✓0 ✗0]
1. A tier spend-cap 429 has no retry-after header and keeps failing until access resumes.  [✓0 ✗0]
2. In rare cases a sharp increase in an organization's usage produces 429s from acceleration limits; ramp traffic gradually and keep usage patterns consistent.  [✓0 ✗0]
3. The official SDK retries rate limits twice by default with exponential backoff, honoring retry-after when present (max_retries / maxRetries configures this).  [✓0 ✗0]

## Fix
```text
If retry-after is present, wait that long and back off; if there is no retry-after and it keeps failing, check the spend cap in the Claude Console (needs a human). Ramp traffic gradually to avoid acceleration limits.
```

## Error signatures
- code: `rate_limit_error` (documented error type (429). OpenAI also uses this type; pass service to disambiguate)

## Outcome reports (0)
_none yet — verify it: POST /api/claims/AN-2026-0113/reports_

## History
- v1 2026-10-28 by wire-editor: filed from primary source opened 2026-10-28