{"openapi":"3.1.0","info":{"title":"California LLC Tax and Fee Calculator API","version":"0.1.0","description":"Compute a California LLC's $800 annual tax and its income-based LLC fee from owner-supplied figures, check whether the first-year $800 exemption (AB 85: organized or registered on or after 2021-01-01 and before 2024-01-01) applies, and get the exact due dates for a tax year: annual tax (Form FTB 3522, the 15th day of the 4th month of the tax year), estimated fee (Form FTB 3536, the 15th day of...\n\nEvery operation is read-only or compute-only. The same tools are available over MCP (streamable HTTP) at https://us-ca-llc-fee.connectorbay.com/mcp.\n\nDisclaimer: General information only, not legal, tax, accounting or payment advice. California LLC Tax and Fee Calculator 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-ca-llc-fee/docs"},"termsOfService":"https://connectorbay.com/us-ca-llc-fee/terms"},"servers":[{"url":"https://us-ca-llc-fee.connectorbay.com"}],"externalDocs":{"url":"https://connectorbay.com/us-ca-llc-fee/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/annual_tax_due":{"post":{"operationId":"annual_tax_due","summary":"Return the $800 annual LLC tax and its due date (the 15th day of the 4th month of the taxable year) for a taxable year, ","description":"Return the $800 annual LLC tax and its due date (the 15th day of the 4th month of the taxable year) for a taxable year, with the first-year exemption applied where it covers the year. Use for \"When is the $800 California LLC annual tax due for 2026, and what about a new LLC formed on 18 June 2026?\".","tags":["tools"],"requestBody":{"required":true,"content":{"application/json":{"schema":{"properties":{"tax_year_start":{"description":"First day of the LLC's taxable year, YYYY-MM-DD, between 2021-01-01 and 2028-12-31 (2026-01-01 for a calendar-year LLC in 2026; for the first year, the Secretary of State filing date).","title":"Tax Year Start","type":"string"},"sos_filing_date":{"anyOf":[{"type":"string"},{"type":"null"}],"default":null,"description":"Optional Secretary of State filing date; when it equals tax_year_start the year is the first taxable year and the AB 85 exemption is checked.","title":"Sos Filing Date"}},"required":["tax_year_start"],"title":"annual_tax_dueArguments","type":"object"}}}},"responses":{"200":{"description":"Tool result. `ok: true` on success; `ok: false` with a structured `error` (provider_unavailable, upstream_error, bad_input) when the tool could not answer.","content":{"application/json":{"schema":{"type":"object","additionalProperties":true}}}},"422":{"description":"Arguments failed validation","content":{"application/json":{"schema":{"$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/llc_fee":{"post":{"operationId":"llc_fee","summary":"Return the California LLC fee for total income (zero below $250,000; $900; $2,500; $6,000; $11,790) with the bracket and","description":"Return the California LLC fee for total income (zero below $250,000; $900; $2,500; $6,000; $11,790) with the bracket and the definition of total income. Use for \"My California LLC had $730,000 of total income. What is the LLC fee?\".","tags":["tools"],"requestBody":{"required":true,"content":{"application/json":{"schema":{"properties":{"total_income":{"anyOf":[{"type":"string"},{"type":"integer"},{"type":"number"}],"description":"Total income for the fee in US dollars: gross income (R&TC 24271) plus cost of goods sold, as a plain decimal (digits, at most 2 decimals; no $ sign or commas). Rounded to the nearest whole dollar (half up).","title":"Total Income"}},"required":["total_income"],"title":"llc_feeArguments","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/first_year_exemption":{"post":{"operationId":"first_year_exemption","summary":"Check whether an LLC filed with the Secretary of State on or after 2021-01-01 and before 2024-01-01 and so had the AB 85","description":"Check whether an LLC filed with the Secretary of State on or after 2021-01-01 and before 2024-01-01 and so had the AB 85 first-year exemption from the $800 tax. Use for \"My LLC was registered in California on 15 August 2022. Did it owe the $800 in its first year?\".","tags":["tools"],"requestBody":{"required":true,"content":{"application/json":{"schema":{"properties":{"sos_filing_date":{"description":"Date the LLC's articles of organization (or registration) were filed with the California Secretary of State, YYYY-MM-DD. Its first taxable year begins on this date.","title":"Sos Filing Date","type":"string"}},"required":["sos_filing_date"],"title":"first_year_exemptionArguments","type":"object"}}}},"responses":{"200":{"description":"Tool result. `ok: true` on success; `ok: false` with a structured `error` (provider_unavailable, upstream_error, bad_input) when the tool could not answer.","content":{"application/json":{"schema":{"type":"object","additionalProperties":true}}}},"422":{"description":"Arguments failed validation","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}},"429":{"description":"Rate limit exceeded (see Retry-After)","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}}},"x-read-only":true}},"/v1/tools/form_568_due":{"post":{"operationId":"form_568_due","summary":"Return the Form 568 due date (the 15th day of the 3rd month after the close of the tax year) and the extended date, with","description":"Return the Form 568 due date (the 15th day of the 3rd month after the close of the tax year) and the extended date, with the weekend and holiday rule. Use for \"When is my California LLC's Form 568 due for the year ending 31 December 2026?\".","tags":["tools"],"requestBody":{"required":true,"content":{"application/json":{"schema":{"properties":{"tax_year_end":{"description":"Last day of the taxable year, YYYY-MM-DD, between 2024-01-01 and 2028-12-31 (only its year and month are used).","title":"Tax Year End","type":"string"}},"required":["tax_year_end"],"title":"form_568_dueArguments","type":"object"}}}},"responses":{"200":{"description":"Tool result. `ok: true` on success; `ok: false` with a structured `error` (provider_unavailable, upstream_error, bad_input) when the tool could not answer.","content":{"application/json":{"schema":{"type":"object","additionalProperties":true}}}},"422":{"description":"Arguments failed validation","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}},"429":{"description":"Rate limit exceeded (see Retry-After)","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}}},"x-read-only":true}},"/v1/tools/estimated_fee_due":{"post":{"operationId":"estimated_fee_due","summary":"Return the Form FTB 3536 estimated LLC fee due date (the 15th day of the 6th month of the tax year) and the underpayment","description":"Return the Form FTB 3536 estimated LLC fee due date (the 15th day of the 6th month of the tax year) and the underpayment penalty rule. Use for \"When do I have to pay the estimated LLC fee for 2026?\".","tags":["tools"],"requestBody":{"required":true,"content":{"application/json":{"schema":{"properties":{"tax_year_start":{"description":"First day of the LLC's taxable year, YYYY-MM-DD, between 2021-01-01 and 2028-12-31 (2026-01-01 for a calendar-year LLC in 2026; for the first year, the Secretary of State filing date).","title":"Tax Year Start","type":"string"}},"required":["tax_year_start"],"title":"estimated_fee_dueArguments","type":"object"}}}},"responses":{"200":{"description":"Tool result. `ok: true` on success; `ok: false` with a structured `error` (provider_unavailable, upstream_error, bad_input) when the tool could not answer.","content":{"application/json":{"schema":{"type":"object","additionalProperties":true}}}},"422":{"description":"Arguments failed validation","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}},"429":{"description":"Rate limit exceeded (see Retry-After)","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}}},"x-read-only":true}},"/v1/tools/annual_calendar":{"post":{"operationId":"annual_calendar","summary":"List every California LLC date for one taxable year (annual tax, estimated fee, Form 568, extended Form 568) with amount","description":"List every California LLC date for one taxable year (annual tax, estimated fee, Form 568, extended Form 568) with amounts and the weekend rule, for the owner to approve as reminders. Use for \"List all my California LLC's tax dates for 2026.\".","tags":["tools"],"requestBody":{"required":true,"content":{"application/json":{"schema":{"properties":{"sos_filing_date":{"description":"Date the LLC's articles of organization (or registration) were filed with the California Secretary of State, YYYY-MM-DD. Its first taxable year begins on this date.","title":"Sos Filing Date","type":"string"},"tax_year":{"description":"Calendar year in which the taxable year ends, 2021 to 2028.","title":"Tax Year","type":"integer"},"fiscal_year_end_month":{"anyOf":[{"type":"integer"},{"type":"null"}],"default":12,"description":"Month the tax year ends, 1 to 12. Default 12 (calendar year).","title":"Fiscal Year End Month"},"total_income":{"anyOf":[{"type":"string"},{"type":"integer"},{"type":"number"},{"type":"null"}],"default":null,"description":"Optional total income for the year (plain decimal) to show the fee amount instead of the bracket table.","title":"Total Income"}},"required":["sos_filing_date","tax_year"],"title":"annual_calendarArguments","type":"object"}}}},"responses":{"200":{"description":"Tool result. `ok: true` on success; `ok: false` with a structured `error` (provider_unavailable, upstream_error, bad_input) when the tool could not answer.","content":{"application/json":{"schema":{"type":"object","additionalProperties":true}}}},"422":{"description":"Arguments failed validation","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}},"429":{"description":"Rate limit exceeded (see Retry-After)","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Error"}}}}},"x-read-only":true}}}}