PayPeriodsPerYear

This property numerically defines the pay period to be used in calculations. This value defaults to 12, which corresponds to a monthly pay period. The Earnings property and the TaxAmount method are expressed in terms of this same pay period.

For example, suppose we have

.NET

// using TaxControls;
try {
  CTaxControl tc = new CTaxControl();
  tc.DataFilename = "us.dat";
  tc.SelectedTax = "fit";
  // 12 for monthly:
  tc.PayPeriodsPerYear = 12;
  tc.Earnings = 1000.00;
  Console.WriteLine(jc.TaxAmount());
} catch (TaxControlException e) {
  Console.WriteLine(e.Message);
}

Java

//import com.boondocks.taxcontrols.*;
try {
  tc.setDataFilename("us.dat");
  tc.setSelectedTax("fit");
  // 12 for monthly:
  tc.setPayPeriodsPerYear(12);
  tc.setEarnings(1000.00);
  System.out.println(tc.TaxAmount());
} catch (TaxControlException e) {
  e.printStackTrace();
}

giving a TaxAmount of $150. The Earnings and TaxAmount are both considered monthly figures.

If we were to change PayPeriodsPerYear to 24:

.NET

// using TaxControls;
try {
  TaxControl tc = new TaxControl();
  tc.setDataFilename("us.dat");
  tc.setSelectedTax("fit");
  // now 24 for semi-monthly:
  tc.setPayPeriodsPerYear(24);
  tc.setEarnings(1000.00);
  Console.WriteLine(jc.TaxAmount());
} catch (TaxControlException e) {
  Console.WriteLine(e.Message);
}

Java

//import com.boondocks.taxcontrols.*;
try {
  tc.setDataFilename("us.dat");
  tc.setSelectedTax("fit");
  // 24 for semi-monthly:
  tc.setPayPeriodsPerYear(24);
  tc.setEarnings(1000.00);
  System.out.println(tc.TaxAmount());
} catch (TaxControlException e) {
  e.printStackTrace();
}

the $1000 Earnings value would now correspond to a semi-monthly figure, and TaxAmount would produce a new semi-monthly tax figure, in all likelihood not $150. (This is because many taxes are based on brackets which determine the tax rate.)