I need to know what factors goes into calculating the cost of employees. I know there are taxes, but how do I figure the overhead such as my G/L and W/C?

There are many factors that go into the cost of employees:

Health, Dental, Vision insurance (employer's portion)
Worker's Compensation
SUTA, FUTA, FICA taxes
Vacation Time, Personal Time, Holiday Pay
Regular Wages and Overtime Wages
401K or Pension employer match
Employee Incentives, Events, Awards

For the insurance you need to find all the insurance that you furnish to the employees
(Health, Vision, Dental, HRA, STD, LTD any other insurance the employer pays for)
Find out what the company is paying for each employee. Take that amount times the total employees. You can find the amounts on your monthly billings.

Worker's Compensation is a percentage of gross wages usually or a set amount if you have private coverage. If it is a per cent take the percent of the total salary. If it is a set amount use the billing to find out how much. If you want to allocate to single employee amount divide the billing by the total employees and you will get an average amount.

Payroll taxes are also percentages of total gross salary.

Vacation, Holiday and PTO time are figured on salary paid you should be able to get those amounts from your payroll system.

Regular and Overtime wages you can also get from your payroll system.

401K match is the total that is matched for each employee's pension plan.

To figure employee incentives and events amounts figure the total of the event or incentive and divide it by the number of employees for an average for each employee.

Now you get all your figures together and you have the payroll costs.

Shirley