ILSIT - Illinois State Income Tax (Illinois Income Tax Withholding)

Just starting the first payroll of the 2019 year and I was verifying the calculations from Sage 50 verses online calculators such as paycheckcity.com.  Three out of the four (4) paychecks matched perfectly with the online double check.  The disconnect is with the Illinois income tax withholding calculation.  I verified the online calculators with the IL withholding tables available online as a .pdf download and the online calculators match perfectly with the manual calculation.

For reference the 2018 and 2019 Illinois Income Tax Withholding is the same value at 4.95% and all Sage 50 payroll updates have been done to date including the January 2019 release.

Since three (3) out of the four (4) paychecks match up perfectly for IL withholding I have to assume it is a problem with the employees account for the individual set-up.

I checked the employees account and I can find no errors.  So I set-up a dummy employee to see if I can get the mistake to repeat and sure enough the mistake is still there.

Employee information

$16.50/hr, 40 hours per week, four (4) withholding allowances for Federal and State, no additional withholding allowances

IL withholding should be $24.01, Sage 50 is currently calculating it at $25.05.

Looking at the variables between the correct calculations and this one there is two (2).

Variable #1 - The three (3) that are calculating correctly are salaried employees and the one that is calculating incorrectly is hourly.

Variable #2 - The three (3) that are calculating correctly have no withholding allowances while the one that is calculating incorrectly has four (4) allowances for Federal and State.

My guess is that Sage has a calculation problem when you have allowances used.  Not good.

Good thing is that we withheld too much instead of too little.

Did some further trail and error and back calculating and saw that we had the same problem for all of 2018.  Not good.

Hoping to see if someone could plug the variables in for the employee that I used to see if you come out with $25.05 (Sage calculated) instead of the correct $24.01 for IL Income Tax Withholding.

I find it hard to believe that no one who did payroll for the state of Illinois has not seen this as well for 2018 and now 2019.

I'm hoping it is a mistake on my part somewhere that I have not thought of.