State Tax

Illinois Education Expense Credit K-12

Illinois Education Expense Credit K-12

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Property Tax Lookup

Index of Illinois Tax Publications

Index of Illinois Tax Publications

Blended Income Tax Rates for use with 2017 Illinois Income Tax Returns (IL Schedule SA)

PDF: Blended Income Tax Rates for use with 2017 Illinois Income Tax Returns (IL Schedule SA)


Effective July 1, 2017, Illinois individual income tax rates increased from 3.75 percent (.0375) to 4.95 percent (.0495). These new income tax rates are effective for income received on or after July 1, 2017. The individual income tax rate for a 2017 will be the blended rate of 4.3549% (.043549). This rate will be shown on your 2017 IL-1040 return.

For tax year 2017, income tax is calculated as follows: the amount earned prior to July 1, 2017, is taxed at 3.75 percent, while the amount earned on or after July 1, 2017, is taxed at 4.95 percent. The two tax amounts must be added together to figure the total tax liability.

For tax year 2017, you may select one of the following methods to calculate the amount of income tax due:

  • Method 1 - Apportionment method (blended rate). The apportionment method is figured by dividing the net income received based on the total number of days in one accounting period in equal ratio to the total number of days in the second accounting period. A convenient way to use this method is to calculate a blended income tax rate and apply it to your total net income. This method is encouraged by the IL Dept of Revenue and is the way that TaxWise calculates the tax. It is the simpler of the two methods and does not require you to attach any additional schedules to your return. If you use the blended rate, do not complete Schedule SA, Specific Accounting.
  • Method 2 - Specific accounting method. The specific accounting method allows you to treat your income as though it were received in two different taxable years (prior to July 1, 2017, and after June 30, 2017) and calculate the income tax due at the applicable rate for each period. You must complete Schedule SA to use this method. See the Instructions section below.


Blended Income Tax Rates For Use With Your 2017 Illinois Income Tax Returns, Illinois Department of Revenue Informational Bulletin, FY 2018-14 November 2017

Steps 1-3

Instructions for using the Specific Accounting Method

By default, TaxWise uses the Apportionment method (blended rate). If you choose to use the Specific Accounting Method, you must complete Schedule SA outside of TaxWise and then manually correct the income tax figures shown on the printed TaxWise IL return.

Step 1 – Complete the Federal and State tax returns as normal.

Step 2 – Indicate that the State return will be Paper, not e-file. The Federal return can still be e-filed if desired.

Step 3 – On line 13 of the IL return, check the box to indicate you’ve completed Schedule SA to calculate the income tax.

Step 3

Step 4 – Complete Schedule SA.

Link to Schedule SA Form
Link to Schedule SA Instructions

To complete Schedule SA, use your computer to fill in the fillable PDF form and then print the completed form, or print out the blank form and fill in by hand. Ensure the Schedule SA calculated income tax is lower than that calculated by TaxWise using the blended rate.

Steps 5-6

Step 5 – Run Diagnostics and have the return quality reviewed. Using a copier, make a copy of Schedule SA. Print out two paper copies of the IL return.

Step 6 – Starting with line 13 and continuing through the balance of the return, strike a line through any value that deals with income tax. Manually write the corrected amount next to each value that has been lined out. Repeat on the other paper IL return.

Step 6a

Step 6b

Step 6c

Step 7

Step 7 – include both copies of Schedule SA in the packet that will be sorted.

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