Determine Your Obligation Assessment

For the convenience of our employer customers, below are instructions to help you figure your 2018 obligation assessment.

The 2018 rates are as follows:

  • OA ratio = 0.171757
  • Base assessment = $63.00
  • Taxable wage base=$9,000

The example calculation below is based on a fictional employer with a 2018 tax rate of 10.30% and 1,500 employees.


  1. Divide your tax rate (10.3) by 100.  The result should be 0.103.
  2. Next, multiply 0.103 by the OA Ratio of 0.171757 (0.103 X 0,0.171757).  Did you get 0.017690971?  Good, that’s correct.  Jot this number down.
  3. Now divide the Base Assessment by the Taxable Wage Base (63/9000).  You should get 0.007.  Next, add this number to the number you saved above and multiply the result by 100. (0.017690971 + 0.007 X 100).  If you get 2.4690971, you’re right.  Always round up this number to the next hundredths of a percent.  So now you should have 2.47.  This is your 2018 OA Rate (2.47%).
  4. To obtain your cost per employee, multiply this example’s OA Rate of 2.47 by the taxable wage base of $9,000.  You should get a cost per employee of $222.30.
  5. To obtain the total cost for the example employer, enter the cost per employee of $222.30 and multiply it by the number of employees, which is 1,500 in this example.  You should get $355,450 as the total cost for the example employer. 

Example Results Summary:

  • OA Rate = 2.47
  • Cost Per Employee = $222.30
  • Total Cost For Employer = $333,450

‚Äč *Since most employers qualified for the $9,000 taxable wage base, this was used in the calculation instead of the higher taxable wage base of $9,500.