The cost of compensation typically includes base pay (wage or salary) and amounts paid by the employer for legally required and other benefits. According to a survey of U.S. Bureau of Labor Statistics (BLS) data, the average cost of benefits as a percentage of total compensation has increased from around 20 percent in 1966 to nearly 30 percent today.

Base and Supplemental Pay

Base pay is the contracted amount an employer pays employees. This is frequently expressed as an hourly wage. Any supplemental amounts paid to employees, including bonuses or overtime pay, is considered a benefit, and accounts for about 2.4 percent of total compensation. The percentage of total compensation attributable to overtime pay depends both on the employer’s practice with respect to assigning overtime and the percentage of the workforce classified as non-exempt, and thus eligible for overtime pay.

Insurance Benefits

Many employers sponsor health insurance benefits for their employees and pay a portion of the premiums. The exact amount of the employer’s share of health insurance premiums varies greatly from employer to employer, with state and local governments typically paying much more than private employers. Overall, employer-paid insurance premiums represent 8.5 percent of total compensation; other insurance premiums, especially life insurance, account for another 0.5 percent of total compensation.

Retirement and Savings

Employers who offer retirement, pension or other income protection benefits spent 4.8 percent of total compensation toward defined contribution and defined benefit plans. Companies that offer short periods for vesting money to which both the employee and employer contribute may experience higher percents of employee benefit costs when they are required to liquidate retirement savings plan amounts upon an employee's departure.

Paid Leave

Paid leave includes any time paid which is not actually worked. There are generally four types of paid leave: paid holidays, paid vacation, sick days, and personal days, On average, paid time off accounts for about 7 percent of the total compensation costs paid by employers.This amount includes not only the actual amounts paid to employees taking the time off, as well as the associated statutory benefits, but also any amounts paid for temporary replacements.

Statutory Benefits

Employers pay 7.65 percent of the first $117,000 of an employee’s earnings for Social Security and Medicare, and 1.45 percent on earnings above that amount, for Medicare only. Other, smaller statutory benefits paid by the employer are workers’ compensation and unemployment tax. According to BLS data for December 2013, these legally required benefits account for 7.8 percent of the average civilian worker’s total compensation cost.