Key legal question
Whether source tax had to be calculated on the basis of annual income or an hourly wage rate.
Extracted holding
The source tax had to be calculated on the taxpayer's annual income because the employment was regular throughout the year; applying an hourly wage rate was incorrect.
Extracted reasoning
The decisive factor was that the taxpayer worked regularly during the entire year. In that situation, the tax base is the annual income actually earned, not a notional hourly rate derived from the number of teaching hours.