{
  "publisher": {
    "name": "Provedays",
    "url": "https://provedays.com"
  },
  "license": "CC BY 4.0",
  "license_url": "https://creativecommons.org/licenses/by/4.0/",
  "attribution": "Provedays — provedays.com",
  "notice": "Rule data is licensed CC BY 4.0. Golden test fixtures, guide prose and the rule schema are not covered by this licence and remain all rights reserved. See https://provedays.com/terms/.",
  "documentation": "https://provedays.com/methodology/",
  "rule_id": "us.federal.spt",
  "versions": [
    {
      "rule_id": "us.federal.spt",
      "version": "2026.1",
      "jurisdiction": "US",
      "title": "US Substantial Presence Test",
      "summary": "You meet the Substantial Presence Test if you are present in the US at least 31 days in the current year AND your weighted total reaches 183: all current-year days, plus one third of last year's days, plus one sixth of the year before. Any part of a day present counts (with narrow exceptions such as certain transit and commuting days). Meeting the test makes you a US tax resident unless an exception (closer connection, treaty) applies.",
      "evaluator": "lookback_aggregation",
      "determinative": true,
      "official_source_url": "https://www.irs.gov/individuals/international-taxpayers/substantial-presence-test",
      "last_verified": "2026-08-28",
      "effective_from": "2000-01-01",
      "effective_to": null,
      "disclaimer_level": "standard",
      "convention": {
        "part_day_counts": true,
        "transit_excluded": true
      },
      "params": {
        "reference_period": {
          "type": "calendar_year"
        },
        "lookback": {
          "periods": 3,
          "total_threshold": 183,
          "weights_sixths": [
            6,
            2,
            1
          ],
          "current_period_minimum": 31
        }
      },
      "notifications": [
        {
          "at_count": 170,
          "at_fraction_of_limit": null,
          "message_key": "us.spt.approaching"
        }
      ],
      "notes": [
        "Weighted arithmetic is exact in sixths (SEMANTICS.md #16): 6*current + 2*prior + 1*second >= 1098.",
        "Exempt individuals (F/J students, diplomats), medical-condition days and <24h transit days are excluded via labels/attestations — Phase 2 for the exemption questionnaire."
      ]
    }
  ]
}