A business that has employees must withhold income taxes on payments to each employee. Each employee must first fill out Form W-4, Employee’s Withholding Allowance Certificate, and provide it to the employer. On the form the employee can claim exemptions, such as the personal exemption or an exemption for a spouse or child, and determine the number of withholding allowances for the employee. Based on that information, the employer calculates the employee’s income tax withholding for the year.

The employer next must select a withholding method. The amount of taxes withheld can be determined using the percentage method; the wage bracket method; the alternative formula table method; or any other method that produces substantially the same amount as the wage bracket method. These methods are based upon tables produced by the IRS and available in IRS publication Circular E, Employer’s Tax Guide.

Percentage Method

The employer must select one of eight tables, based on the payroll period used by the employer, such as weekly, monthly, annually, etc. If the employer does not use a payroll period, it should use the daily or miscellaneous table. Each table is divided into two parts: one for single people, and one for married people.

After determining the appropriate table, the employer must determine the amount of wages to use as the base calculation. This amount is determined by subtracting the number of withholding allowances from the employee’s total gross wages for the payroll period. The result is net wages subject to withholding. The result is used in the withholding tables to determine the withholding amount.

Wage Bracket Method

For each employee, the employer again must determine the payroll period, wages paid during the period, withholding exemptions, and marital status. The wage bracket tables calculate the income tax to deduct and withhold by using gross wages, with no deduction for an exemption amount. This method is supposed to produce similar results to the percentage method.

The wage bracket method cannot be used if the payroll period is quarterly, semiannual, or annual, because there are no tables for these periods.

Other methods

The third method—alternative formula tables—is for employers using computerized accounting systems. The fourth method is allowed if it produces substantially similar results to the wage bracket method. The IRS provides a table for determining whether a result is substantially similar.

Other Employment Taxes

Employers must also determine FICA (Federal Insurance Contributions Act [Social Security]) and Federal Unemployment Tax Act (FUTA) taxes.

FICA consists of two taxes: the old-age, survivors and disability insurance (OASDI) tax, equal to 6.2 percent on both the employer and employee; and the hospital insurance (HI) tax, equal to 1.45 percent on both the employer and the employee. FICA taxes thus have a combined rate of 7.65 percent. The OASDI tax is subject to a wage limit, set at $118,500 for 2015 and 2016, but subject to increase. Wages above that limit are exempt from the OASDI tax. However, there is no limit on the HI tax; all wages are taxed 1.45 percent. The IRS provides tables to determine FICA taxes.

If the employee has wages in excess of $200,000, the employer must also withhold the Additional 0.9 percent Medicare tax from all wages above that threshold.

FUTA tax is 6 percent of all wages paid during the calendar year, up to a $7,000 wage limit. These amounts are owed by the employer and are not deducted from the employee’s wages. The employer can claim a credit for contributions to state unemployment insurance funds. The maximum credit is 90 percent of the 6 percent rate, or 5.4 percent.