How the finder decides
- Class 1 is the default when neither Class 1a nor Class 2 applies.
- Class 1a generally covers qualifying single parents, people aged 65 or older at the start of the year, and widowed taxpayers outside the Class 2 transition.
- Class 2 generally covers qualifying joint taxation and certain three-year transition periods.
- Individual rate applies when a fixed rate is printed on an additional tax card or follows certain elections.
Non-resident assimilation, mixed-residence couples, and transitional treatment can depend on income tests, applications, and prior use.