{"openapi":"3.1.0","info":{"title":"US ACH Timing and Rules API","version":"0.1.0","description":"US ACH Timing and Rules answers date questions for a business that originates ACH payments through its bank. same_day_limit_check compares an amount with the Same Day ACH per-entry limit that applies on a date ($1 million until 16 September 2027, $10 million from 17 September 2027, as Nacha publishes). funds_availability_rule states the 9:00 am receiving-bank rule for non-Same Day credits from 18...\n\nEvery operation is read-only or compute-only. The same tools are available over MCP (streamable HTTP) at https://us-ach-timing.connectorbay.com/mcp.\n\nDisclaimer: General information only, not legal, tax, accounting or payment advice. US ACH Timing and Rules is an independent tool: it is not affiliated with, endorsed by or operated by any government body, central bank, standards body or scheme operator. Rates, thresholds and rules change; check the cited official source and confirm with a qualified professional before you rely on a result.","contact":{"name":"Unify Dynamics LLC","email":"agent@connectorbay.com","url":"https://connectorbay.com/us-ach-timing/docs"},"termsOfService":"https://connectorbay.com/us-ach-timing/terms"},"servers":[{"url":"https://us-ach-timing.connectorbay.com"}],"externalDocs":{"url":"https://connectorbay.com/us-ach-timing/docs"},"security":[{},{"bearer":[]}],"components":{"securitySchemes":{"bearer":{"type":"http","scheme":"bearer","description":"Optional. A Pro API key raises rate limits; no credentials are required."}},"schemas":{"Error":{"type":"object","properties":{"ok":{"const":false},"error":{"type":"object"}}}}},"paths":{"/v1/tools/same_day_limit_check":{"post":{"operationId":"same_day_limit_check","summary":"Check an amount against the Nacha Same Day ACH per-entry limit that applies on a date ($1 million until 2027-09-16, $10 ","description":"Check an amount against the Nacha Same Day ACH per-entry limit that applies on a date ($1 million until 2027-09-16, $10 million from 2027-09-17). Use for \"Can I send a $2,500,000 Same Day ACH payment today, and when does the limit change?\".","tags":["tools"],"requestBody":{"required":true,"content":{"application/json":{"schema":{"properties":{"amount":{"description":"Amount of one entry in US dollars as a decimal string (for example 2500000.00; commas allowed)","title":"Amount","type":"string"},"on_date":{"anyOf":[{"type":"string"},{"type":"null"}],"default":null,"description":"Calendar date YYYY-MM-DD the answer is stated for; defaults to today (UTC) and the answer says which date was used","title":"On Date"}},"required":["amount"],"title":"same_day_limit_checkArguments","type":"object"}}}},"responses":{"200":{"description":"Tool result. `ok: true` on success; `ok: false` with a structured `error` (provider_unavailable, upstream_error, bad_input) when the tool could not answer.","content":{"application/json":{"schema":{"type":"object","additionalProperties":true}}}},"422":{"description":"Arguments failed validation","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}},"429":{"description":"Rate limit exceeded (see Retry-After)","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}}},"x-read-only":true}},"/v1/tools/funds_availability_rule":{"post":{"operationId":"funds_availability_rule","summary":"State the receiving-bank funds availability rule for non-Same Day ACH credits on a date (9:00 am local time on the Settl","description":"State the receiving-bank funds availability rule for non-Same Day ACH credits on a date (9:00 am local time on the Settlement Date from 2026-09-18). Use for \"When must a receiving bank make an ACH credit available after the September 2026 rule change?\".","tags":["tools"],"requestBody":{"required":true,"content":{"application/json":{"schema":{"properties":{"on_date":{"anyOf":[{"type":"string"},{"type":"null"}],"default":null,"description":"Calendar date YYYY-MM-DD the answer is stated for; defaults to today (UTC) and the answer says which date was used","title":"On Date"}},"title":"funds_availability_ruleArguments","type":"object"}}}},"responses":{"200":{"description":"Tool result. `ok: true` on success; `ok: false` with a structured `error` (provider_unavailable, upstream_error, bad_input) when the tool could not answer.","content":{"application/json":{"schema":{"type":"object","additionalProperties":true}}}},"422":{"description":"Arguments failed validation","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}},"429":{"description":"Rate limit exceeded (see Retry-After)","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}}},"x-read-only":true}},"/v1/tools/nacha_changes_since":{"post":{"operationId":"nacha_changes_since","summary":"List published Nacha Operating Rules changes with effective dates in a date range and whether each is in force on a date","description":"List published Nacha Operating Rules changes with effective dates in a date range and whether each is in force on a date. Use for \"Which Nacha rule changes take effect after 1 September 2026, and which are already in force?\".","tags":["tools"],"requestBody":{"required":true,"content":{"application/json":{"schema":{"properties":{"since":{"description":"First effective date to include, YYYY-MM-DD (2026-01-01 or later)","title":"Since","type":"string"},"until":{"anyOf":[{"type":"string"},{"type":"null"}],"default":null,"description":"Last effective date to include, YYYY-MM-DD (default: no upper bound)","title":"Until"},"on_date":{"anyOf":[{"type":"string"},{"type":"null"}],"default":null,"description":"Calendar date YYYY-MM-DD the answer is stated for; defaults to today (UTC) and the answer says which date was used","title":"On Date"}},"required":["since"],"title":"nacha_changes_sinceArguments","type":"object"}}}},"responses":{"200":{"description":"Tool result. `ok: true` on success; `ok: false` with a structured `error` (provider_unavailable, upstream_error, bad_input) when the tool could not answer.","content":{"application/json":{"schema":{"type":"object","additionalProperties":true}}}},"422":{"description":"Arguments failed validation","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}},"429":{"description":"Rate limit exceeded (see Retry-After)","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}}},"x-read-only":true}},"/v1/tools/explain_rule":{"post":{"operationId":"explain_rule","summary":"Summarise one published Nacha rule change in the wording of Nacha's page, with its effective date and status on a date. ","description":"Summarise one published Nacha rule change in the wording of Nacha's page, with its effective date and status on a date. Use for \"What is the Nacha fraud monitoring rule and when did each phase start?\".","tags":["tools"],"requestBody":{"required":true,"content":{"application/json":{"schema":{"properties":{"rule":{"description":"Rule id: same_day_limit_10m, funds_availability_9am, fraud_monitoring_phase_1, fraud_monitoring_phase_2, company_entry_descriptions, iat_definition, funds_availability_exceptions, treasury_contact_registry, accepted_characters, iat_contact_registration, iat_amendments_2027, r90_sanctions_return","title":"Rule","type":"string"},"on_date":{"anyOf":[{"type":"string"},{"type":"null"}],"default":null,"description":"Calendar date YYYY-MM-DD the answer is stated for; defaults to today (UTC) and the answer says which date was used","title":"On Date"}},"required":["rule"],"title":"explain_ruleArguments","type":"object"}}}},"responses":{"200":{"description":"Tool result. `ok: true` on success; `ok: false` with a structured `error` (provider_unavailable, upstream_error, bad_input) when the tool could not answer.","content":{"application/json":{"schema":{"type":"object","additionalProperties":true}}}},"422":{"description":"Arguments failed validation","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}},"429":{"description":"Rate limit exceeded (see Retry-After)","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}}},"x-read-only":true}},"/v1/tools/fed_holidays":{"post":{"operationId":"fed_holidays","summary":"List Federal Reserve Bank holidays for a year (2026 to 2030) with the days the Reserve Banks are closed under the Saturd","description":"List Federal Reserve Bank holidays for a year (2026 to 2030) with the days the Reserve Banks are closed under the Saturday and Sunday rules. Use for \"Which days in 2027 are Federal Reserve holidays when ACH payments do not settle?\".","tags":["tools"],"requestBody":{"required":true,"content":{"application/json":{"schema":{"properties":{"year":{"description":"Calendar year, 2026 to 2030","maximum":2030,"minimum":2026,"title":"Year","type":"integer"}},"required":["year"],"title":"fed_holidaysArguments","type":"object"}}}},"responses":{"200":{"description":"Tool result. `ok: true` on success; `ok: false` with a structured `error` (provider_unavailable, upstream_error, bad_input) when the tool could not answer.","content":{"application/json":{"schema":{"type":"object","additionalProperties":true}}}},"422":{"description":"Arguments failed validation","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}},"429":{"description":"Rate limit exceeded (see Retry-After)","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}}},"x-read-only":true}},"/v1/tools/next_fed_business_day":{"post":{"operationId":"next_fed_business_day","summary":"Count Federal Reserve business days after a date (the calendar ACH settlement relies on), skipping weekends and Reserve ","description":"Count Federal Reserve business days after a date (the calendar ACH settlement relies on), skipping weekends and Reserve Bank holidays. Use for \"If I send an ACH file on Thursday 2 July 2026, which is the next Federal Reserve business day?\".","tags":["tools"],"requestBody":{"required":true,"content":{"application/json":{"schema":{"properties":{"from_date":{"description":"Start date YYYY-MM-DD (2026-01-01 to 2030-12-31)","title":"From Date","type":"string"},"business_days":{"default":1,"description":"How many Federal Reserve business days after from_date, 1 to 30 (default 1)","maximum":30,"minimum":1,"title":"Business Days","type":"integer"}},"required":["from_date"],"title":"next_fed_business_dayArguments","type":"object"}}}},"responses":{"200":{"description":"Tool result. `ok: true` on success; `ok: false` with a structured `error` (provider_unavailable, upstream_error, bad_input) when the tool could not answer.","content":{"application/json":{"schema":{"type":"object","additionalProperties":true}}}},"422":{"description":"Arguments failed validation","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}},"429":{"description":"Rate limit exceeded (see Retry-After)","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}}},"x-read-only":true}}}}