> ## Documentation Index > Fetch the complete documentation index at: https://docs.symmetry.com/llms.txt > Use this file to discover all available pages before exploring further. # API: SPF to STE tax parameter mapping (U.S.) > Map U.S. SPF API taxParameters to STE via the /spf/steMapping endpoint. Covers response fields, applying mappings in STE, common use cases, plus FAQs. Clients who license both SPF API and the STE can use the `/spf/steMapping` endpoint to get SPF tax parameters that map to STE miscellaneous and standard parameters. Note this applies to SPF U.S. and STE U.S. only. Canadian forms are not included in the endpoint's mapping. ## Overview When an employee completes a withholding form in SPF, the completed form returns **tax parameters** (for example, `FED.filingStatus` or `CA.totalAllowances`). To calculate accurate withholding in the STE, those values must be set to the applicable STE miscellaneous parameter or STE standard parameter within the STE payroll calculation. The `/spf/steMapping` endpoint returns the authoritative mapping between SPF and STE. Each mapping entry includes: * The SPF tax parameter name. * The corresponding STE **miscellaneous** or **standard** parameter. * The STE unique tax ID(s) the parameter applies to. * An **effective date** for when that mapping is active. * Optional **notes** when additional logic is required. The response also includes the SPF and STE release versions the mapping corresponds to, so you can confirm your integration is aligned with the releases you are running. ## Endpoint details ### Request | Item | Value | | -------------- | ---------------------------------------------- | | Method | `GET` | | Path | `/spf/steMapping` | | Authentication | Bearer token (same as other SPF API endpoints) | | Accept header | `application/json` | ### Query parameters | Parameter | Required | Description | | --------------- | -------- | ------------------------------------------------------------------------------------------------------- | | `effectiveDate` | No | ISO-8601 date (`yyyy-MM-dd`). Returns the mapping active as of that date. Defaults to today if omitted. | | `formId` | No | Limits the response to a single form (for example, `W4101` or `AZ101`). | | `version/get` | No | Bypasses authentication and returns endpoint version metadata only. | #### Effective dating When you set the `effectiveDate` query parameter, the endpoint returns the most recent mapping version for each SPF tax parameter where the parameter's `effectiveDate` is on or before your requested date. This lets you: * Look up mappings for historical payroll dates. * Retrieve upcoming mapping changes before they take effect. * Update your integration proactively when Symmetry publishes a new mapping version. ## Response fields | Field | Description | | ------------------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------- | | `spfRelease` | The SPF release the mapping data corresponds to. | | `steRelease` | The STE release the mapping data corresponds to. | | `asOf` | The date the mapping was resolved against. | | `forms` | Array of form-level mapping objects. | | `forms[].formId` | SPF form ID. | | `forms[].formName` | Full form title. | | `forms[].parameters` | Mapping entries for that form. | | `spfTaxParameter` | The SPF tax parameter name from the form output. | | `steMiscellaneousParameter` | STE miscellaneous parameter name, when applicable. Omitted when a standard parameter is used instead. | | `steStandardParameter` | STE standard parameter name, when applicable (for example, `additionalWH` or `isExempt`). Omitted when a miscellaneous parameter is used instead. | | `correspondingSteUniqueTaxIds` | The STE unique tax ID(s) to apply the parameter to. | | `notes` | Additional guidance when the mapping requires special handling. Always review this field when present. | | `effectiveDate` | The date from which this mapping entry is effective (which will always be the effective date of the form). | The `spfRelease` and `steRelease` fields in the `/spf/steMapping` response show which releases the mapping was last verified against. They may not reflect your current SPF or STE release. Treat them as **accurate as of** metadata. We will continue to enhance this endpoint and improve how mapping data is kept current in upcoming releases. ### Example requests Return all U.S. form mappings active today: ```http theme={null} GET /spf/steMapping Authorization: Bearer {accessToken} Accept: application/json ``` Return mappings for Form W-4 (`W4101`) as of January 1, 2026: ```http theme={null} GET /spf/steMapping?formId=W4101&effectiveDate=2026-01-01 Authorization: Bearer {accessToken} Accept: application/json ``` ### Example response ```json theme={null} { "spfRelease": "2026-R5", "steRelease": "2026.5.2", "asOf": "2026-01-01", "forms": [ { "formId": "W4101", "formName": "Form W-4: Employee's Withholding Certificate", "parameters": [ { "spfTaxParameter": "FED.filingStatus", "steMiscellaneousParameter": "FILINGSTATUS", "correspondingSteUniqueTaxIds": ["00-000-0000-FIT-000"], "effectiveDate": "2026-01-01" }, { "spfTaxParameter": "FED.additionalFedWithholding", "steStandardParameter": "additionalWH", "correspondingSteUniqueTaxIds": ["00-000-0000-FIT-000"], "effectiveDate": "2026-01-01" }, { "spfTaxParameter": "FED.nonResidentAlien", "steMiscellaneousParameter": "FILINGSTATUS", "correspondingSteUniqueTaxIds": ["00-000-0000-FIT-000"], "notes": "FED.nonResidentAlien = true; FILINGSTATUS = \"NRA\"", "effectiveDate": "2026-01-01" } ] } ] } ``` ## Applying mappings in the STE Each mapping entry points to either a **miscellaneous** or **standard** STE parameter: * **Standard parameters** (for example, `isExempt` and `additionalWH`) are available for all taxes when you set up a tax within the tax jurisdiction object. * **Miscellaneous parameters** are tax-specific and vary by jurisdiction; these are set within the miscellaneous jurisdiction parameters for each specific tax within the tax jurisdiction object. ## Common use cases ### Automate SPF-to-STE integration After an employee completes a withholding form, call this endpoint (optionally filtered by `formId`) to determine how each SPF tax parameter in the response should be passed into STE. ### Stay current without manual reference updates Instead of maintaining a local copy of a static mapping document, call the endpoint during deployment or on a schedule. Compare the returned `spfRelease` and `steRelease` values to detect when your mapping logic needs to be refreshed. ### Prepare for upcoming mapping changes Query the endpoint with a future `effectiveDate` to retrieve mappings that will become active on that date, then update your integration before the change goes live. ### Support backdated or corrected payroll When processing payroll for a prior check date, pass that date as `effectiveDate` to retrieve the mapping that was active at that time. ### Development and troubleshooting During integration work, filter by a specific `formId` to quickly confirm which STE parameters and tax IDs correspond to a given form's SPF output. ## Frequently asked questions ### Does this endpoint replace the static SPF-to-STE mapping article? For API clients, yes. Hosted and on-premise clients will still need to use the [static mapping article](/spf/references/ste-tax-parameter-mapping). ### Are all SPF tax parameters included? No. Only SPF tax parameters where the value affects the payroll tax calculation in STE are included.