How are contributions to a 401(k) plan typically made?

Contributions to a 401(k) plan are primarily made through payroll deductions. This method allows employees to have a portion of their salary automatically withheld and contributed directly to their retirement savings account. Payroll deductions are beneficial because they make saving for retirement more convenient and consistent, as they occur before employees receive their paychecks. This system also provides tax advantages, as contributions are often made on a pre-tax basis, reducing the employee's taxable income for the year.

Other methods like credit card payments or bank transfers are not standard practices for 401(k) contributions. These methods can introduce complexities and may not align with the structure of plan contributions, which are designed to facilitate regular, systematic savings through the payroll mechanism. Thus, the most reliable and common way for employees to contribute to their 401(k) plans remains via payroll deductions.