Reference
The rules, written out.
Four rule sets decide almost every multi-state payroll question, and they interact. Each page below is the full national picture for one of them.
The convenience-of-the-employer rule
Six jurisdictions tax a remote employee's wages as if the work happened at the employer's office. Here is exactly how each one applies the test, and what displaces it.
Nonresident withholding thresholds
How many days or dollars a nonresident can work in each state before withholding is required, and why crossing the line is usually retroactive to day one.
Which state gets the unemployment wages
Unemployment coverage is never split between states. The localization test decides which single state a job belongs to, and it is applied in strict sequence.
Local income taxes
Sixteen states permit municipal, county or school-district income taxes. State reciprocal agreements almost never cover them, which is where multi-state payroll usually breaks.
Withholding and exemption certificates
The state equivalent of Form W-4 for every jurisdiction, alongside the separate nonresident exemption certificate used to claim reciprocity.
SUI taxable wage bases, 2026
The 2026 taxable wage base, the 2025 comparison, new-employer rates and the experience-rating method each state uses.
Paid family and medical leave
Which states collect a paid-leave payroll contribution in 2026, who pays it, and which programmes are enacted but not yet collecting.
Employer registration by state
The revenue agency and the workforce agency you register with in each jurisdiction, and why one remote hire usually means two applications.