StateSide

Determination engine

Which state do you actually withhold in?

Reciprocity, convenience-of-the-employer, nonresident thresholds and unemployment localization, applied together to one employee's facts. Every answer cites the state source it came from.

Withholding determination

Answer six questions. The result is a shareable link, so you can paste it into a ticket or an email.

Run a whole roster instead

What the engine resolves

Four questions that a payroll system will not answer for you, and that no single state's guidance covers end to end.

Reciprocity

17 jurisdictions have reciprocal agreements, each with its own exemption certificate that must be on file before the exemption is real.

Convenience of the employer

6 jurisdictions tax remote days as if they happened at the employer's office, creating double taxation the credit does not always relieve.

Nonresident thresholds

25 states let a nonresident work a set number of days or dollars before withholding starts. Crossing the line is retroactive to day one.

SUI localization

Unemployment coverage is never split. The four-factor test assigns one job to exactly one state, and it is applied in strict order.

Common pairs

Full write-ups for the state combinations that generate the most questions.

Live in California, work in ArizonaLive in Indiana, work in ArizonaLive in Oregon, work in ArizonaLive in Virginia, work in ArizonaLive in Illinois, work in IowaLive in Iowa, work in IllinoisLive in Kentucky, work in IllinoisLive in Michigan, work in IllinoisLive in Wisconsin, work in IllinoisLive in Kentucky, work in IndianaLive in Michigan, work in IndianaLive in Ohio, work in IndianaLive in New Jersey, work in New YorkLive in Connecticut, work in New YorkLive in Pennsylvania, work in New YorkLive in Florida, work in New YorkLive in North Carolina, work in New YorkLive in New York, work in New JerseyLive in New York, work in ConnecticutLive in Massachusetts, work in ConnecticutLive in New Hampshire, work in MassachusettsLive in Rhode Island, work in MassachusettsLive in Connecticut, work in MassachusettsLive in Nevada, work in California

Coverage

Jurisdictions
51
All 50 states plus the District of Columbia.
Reciprocal agreements
17
Verified against the exemption forms themselves, not secondary summaries.
Written pair analyses
152
Every real agreement, plus the highest-volume non-reciprocal combinations.
Data currency
2026
SUI wage bases, PFML contributions and forms current for the 2026 tax year.
This is a determination aid, not advice. StateSide encodes published state rules and applies them mechanically to the facts you enter. It does not know your entity structure, your nexus history, your equity compensation, or the dozens of exceptions that turn a clean rule into a judgement call. Every determination cites the state source it came from — verify against that source, and take anything consequential to a payroll tax professional before you act on it.