StateSide

JSON API

Keyless, CORS-enabled. Single determinations by GET, whole rosters by POST.

Single determination

curl -s "https://statesidetax.online/api/determine?res=NJ&work=PA&employer=PA&days=220"

Parameters: res, work, employer (two-letter codes), optional days, wages, remote=1, necessity=1. Returns the withholding state, certificate, SUI state, every finding and the registrations required.

Whole roster

curl -s -X POST https://statesidetax.online/api/determine \
  -H 'content-type: application/json' \
  -d '{"rows":[{"name":"A. Rivera","res":"NJ","work":"PA","employer":"PA","days":220}]}'

Up to 2,000 rows per request. Nothing is stored.

State data

curl -s https://statesidetax.online/api/state/PA

The full record for one jurisdiction: rates, certificates, reciprocity, thresholds, local tax notes, SUI parameters and sources.

Reciprocity map

curl -s https://statesidetax.online/api/reciprocity

Every agreement as a map of work state to exempted residence states, plus the convenience-rule, no-income-tax and local-tax state lists.