{"openapi":"3.1.0","info":{"title":"NZ GST Calendar and Threshold API","version":"0.1.0","description":"Read-only reference and arithmetic for New Zealand GST. Finds the due date of a GST return and payment for a taxable period (the 28th of the month after the period ends, with the periods ending 31 March and 30 November due 7 May and 15 January), lists the deadlines that fall in the next N days for a monthly, two-monthly or six-monthly filer, tests turnover against the NZ$60,000 registration...\n\nEvery operation is read-only or compute-only. The same tools are available over MCP (streamable HTTP) at https://nz-gst-calendar.connectorbay.com/mcp.\n\nDisclaimer: General information only, not legal, tax, accounting or payment advice. NZ GST Calendar and Threshold 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/nz-gst-calendar/docs"},"termsOfService":"https://connectorbay.com/nz-gst-calendar/terms"},"servers":[{"url":"https://nz-gst-calendar.connectorbay.com"}],"externalDocs":{"url":"https://connectorbay.com/nz-gst-calendar/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/gst_split":{"post":{"operationId":"gst_split","summary":"Split an amount into net and GST at 15%: from a GST-inclusive amount (3/23) or from a GST-exclusive amount (15%). Use fo","description":"Split an amount into net and GST at 15%: from a GST-inclusive amount (3/23) or from a GST-exclusive amount (15%). Use for \"My customer paid NZ$115 including GST: how much of that is GST?\".","tags":["tools"],"requestBody":{"required":true,"content":{"application/json":{"schema":{"properties":{"amount":{"description":"The amount in NZ dollars as a decimal string","title":"Amount","type":"string"},"basis":{"description":"inclusive when the amount already contains GST, exclusive when GST is still to be added","title":"Basis","type":"string"}},"required":["amount","basis"],"title":"gst_splitArguments","type":"object"}}}},"responses":{"200":{"description":"Tool result. `ok: true` on success; `ok: false` with a structured `error` (provider_unavailable, upstream_error, bad_input) when the tool could not answer.","content":{"application/json":{"schema":{"type":"object","additionalProperties":true}}}},"422":{"description":"Arguments failed validation","content":{"application/json":{"schema":{"$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/check_registration_threshold":{"post":{"operationId":"check_registration_threshold","summary":"Test turnover against the NZ$60,000 registration wording: last 12 months, or expected in the next 12 months. Use for \"My","description":"Test turnover against the NZ$60,000 registration wording: last 12 months, or expected in the next 12 months. Use for \"My sales were NZ$58,000 over the last 12 months and I expect NZ$65,000 in the next 12: do I have to register for GST?\".","tags":["tools"],"requestBody":{"required":true,"content":{"application/json":{"schema":{"properties":{"turnover_last_12_months":{"description":"Turnover of the taxable activity over the last 12 months, in NZ dollars, as a decimal string","title":"Turnover Last 12 Months","type":"string"},"expected_next_12_months":{"anyOf":[{"type":"string"},{"type":"null"}],"default":null,"description":"Turnover expected over the next 12 months, in NZ dollars, as a decimal string; leave out if not estimated","title":"Expected Next 12 Months"}},"required":["turnover_last_12_months"],"title":"check_registration_thresholdArguments","type":"object"}}}},"responses":{"200":{"description":"Tool result. `ok: true` on success; `ok: false` with a structured `error` (provider_unavailable, upstream_error, bad_input) when the tool could not answer.","content":{"application/json":{"schema":{"type":"object","additionalProperties":true}}}},"422":{"description":"Arguments failed validation","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}},"429":{"description":"Rate limit exceeded (see Retry-After)","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}}},"x-read-only":true}},"/v1/tools/next_gst_due":{"post":{"operationId":"next_gst_due","summary":"Due date of the GST return and payment for a taxable period: the 28th rule and the March and November exceptions, plus a","description":"Due date of the GST return and payment for a taxable period: the 28th rule and the March and November exceptions, plus a next-working-day date for 2026 and 2027. Use for \"When is the GST return for the period ending 31 March 2027 due?\".","tags":["tools"],"requestBody":{"required":true,"content":{"application/json":{"schema":{"properties":{"period_end":{"description":"Last day of the taxable period, YYYY-MM-DD (a month-end date)","title":"Period End","type":"string"}},"required":["period_end"],"title":"next_gst_dueArguments","type":"object"}}}},"responses":{"200":{"description":"Tool result. `ok: true` on success; `ok: false` with a structured `error` (provider_unavailable, upstream_error, bad_input) when the tool could not answer.","content":{"application/json":{"schema":{"type":"object","additionalProperties":true}}}},"422":{"description":"Arguments failed validation","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}},"429":{"description":"Rate limit exceeded (see Retry-After)","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}}},"x-read-only":true}},"/v1/tools/upcoming_gst_deadlines":{"post":{"operationId":"upcoming_gst_deadlines","summary":"GST return and payment deadlines falling in the next N days for a filer with a known period end and a filing frequency. ","description":"GST return and payment deadlines falling in the next N days for a filer with a known period end and a filing frequency. Use for \"Every Monday: which GST deadlines fall in the next 14 days for my two-monthly returns?\".","tags":["tools"],"requestBody":{"required":true,"content":{"application/json":{"schema":{"properties":{"period_end":{"description":"The end date of any one taxable period in the filer's cycle, YYYY-MM-DD (a month-end date), for example the last period end","title":"Period End","type":"string"},"filing_frequency":{"description":"monthly, two_monthly or six_monthly","title":"Filing Frequency","type":"string"},"on_date":{"anyOf":[{"type":"string"},{"type":"null"}],"default":null,"description":"First day of the window, YYYY-MM-DD; defaults to today (UTC)","title":"On Date"},"days":{"default":14,"description":"Length of the window in days (1 to 366)","title":"Days","type":"integer"}},"required":["period_end","filing_frequency"],"title":"upcoming_gst_deadlinesArguments","type":"object"}}}},"responses":{"200":{"description":"Tool result. `ok: true` on success; `ok: false` with a structured `error` (provider_unavailable, upstream_error, bad_input) when the tool could not answer.","content":{"application/json":{"schema":{"type":"object","additionalProperties":true}}}},"422":{"description":"Arguments failed validation","content":{"application/json":{"schema":{"$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/filing_frequency_rules":{"post":{"operationId":"filing_frequency_rules","summary":"The GST filing frequencies and the sales limits Inland Revenue states for six-monthly and monthly filing. Use for \"Can I","description":"The GST filing frequencies and the sales limits Inland Revenue states for six-monthly and monthly filing. Use for \"Can I file GST six-monthly if my sales are NZ$300,000 a year?\".","tags":["tools"],"requestBody":{"required":true,"content":{"application/json":{"schema":{"properties":{"sales_last_12_months":{"anyOf":[{"type":"string"},{"type":"null"}],"default":null,"description":"Sales in any 12-month period in NZ dollars, to test against the stated limits; leave out for the rules only","title":"Sales Last 12 Months"}},"title":"filing_frequency_rulesArguments","type":"object"}}}},"responses":{"200":{"description":"Tool result. `ok: true` on success; `ok: false` with a structured `error` (provider_unavailable, upstream_error, bad_input) when the tool could not answer.","content":{"application/json":{"schema":{"type":"object","additionalProperties":true}}}},"422":{"description":"Arguments failed validation","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}},"429":{"description":"Rate limit exceeded (see Retry-After)","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}}},"x-read-only":true}}}}