State codes and filing

The codes a return asks for, and who it goes to.

State codes

Each part's ids repeats what the state's rate data says about that tax: its codes, and who collects it. The whole location's codes are in locationIds. Keys are the publisher's own column names and values are exactly as published, leading zeros and all; we don't check them against a return's code list. Census FIPS codes are in code, never in ids. locationIds is {} when the address could be in areas whose ids differ.

To find the location's filing code without knowing the state, read locationIds[reporting.locationKey]. Read a code by its exact key, and treat every key as possibly absent: fall back to your own lookup rather than guess when it's missing. Keep values as strings. locationCode is OpenTaxRate's own key, not a filing code. The OpenAPI spec names each locationIds key below, so a generated client has them as optional fields.

"parts": [
  { "kind": "state", "name": "Alabama", "code": "45:01", "rate": 0.04, "ids": {} },
  { "kind": "county", "name": "MONTGOMERY COUNTY", "code": "00:101", "rate": 0.025,
    "ids": { "Locality Code": "7051", "County Number": "51", "Administered": "SELF" } },
  { "kind": "city", "name": "MONTGOMERY", "code": "01:51000", "rate": 0.035,
    "ids": { "Locality Code": "9454", "County Number": "51", "Administered": "SELF" } }
]

State	Keys in `ids`
Alabama	`Locality Code`, `County Number`, `Administered` (`STATE`, `SELF` or a private collector). A county rate made of several codes lists each, comma-separated.
Texas	`TAID`; `CMPTRL_CNTY_NBR` and `FIPS_ST_CNTY_CD` for counties, `Transit_Type`, `SPD_Type`
Illinois	`Location Code` with its check digit (`048-0002-8`), `County Name`
Louisiana	`Domicile Code`, `Parish`, `Parish Code`
Arizona	`RegionCode`, and `County` or `FIPS`
New Mexico	`locat_cdr`, `locat_cd1`, `locat_cd2`
Colorado, Alaska	`placeId`, `placeTypeId` (the state lookup's own ids)
Missouri	`Jurisdiction Code`, `District Code 1` to `5`; the location's `Jurisdiction Code` is also in `locationIds`
California	None on parts; the location's `Tax Area Code` (CDTFA's 12 characters, `19034D900000`) and `Local Tax Area Code` (its first five digits, `19034`: county and city, 998 unincorporated, as CDTFA-531-FL1 lists them for a return's schedules) in `locationIds`. No district tax codes yet.
Streamlined states	None on parts; the location's `Composite SER Code` in `locationIds` where the state fills it (zero-padded in Washington: `01726`; Washington also gets the DOR's four-digit `Location Code`, `1726`, the code My DOR files under)
Everywhere else	None yet: `{}`

Reporting

reporting says where the tax is filed.

Field	Description
`agency`	The state agency the return goes to, and its sales tax page.
`form`	The return most sellers file there.
`notes`	Filing that doesn't go through the state: cities that collect their own tax, a separate program for remote sellers.
`locationKey`	The `locationIds` key the return files the location under: `Location Code` in Washington, `Local Tax Area Code` in California, `Jurisdiction Code` in Missouri; `null` elsewhere.