start, change, or stop Federal and State income tax withholdings;

As Simon Black pointed out at the time, these voluntary deductions wouldn't be tax deductible.

Types of voluntary deductions tend to depend on the programs or employee benefits offered by an employer.

To view, start, change or stop a federal voluntary tax deduction, select the “Federal voluntary tax deductions for CPP/OAS” link.

To view, start, change or stop a federal voluntary tax deduction, select the “Federal voluntary tax deductions for CPP/OAS” link.

Even more variable are voluntary deductions, which may include things like contributions to 401ks or to health insurance.