Schedule UB: Combined Apportionment for Unitary Business Group (2025)
Illinois · Illinois DOR · Used for tax years 2025
Illinois Schedule UB reports membership information and calculates combined income for a unitary business group. It includes member income, deductions, adjustments between members, and Illinois additions and subtractions to figure combined unitary business income or loss.
Who files this form
Schedule UB is for combined apportionment for a unitary business group. The form directs filers to attach it to Form IL-1120, Form IL-1120-ST, or Form IL-1065.
The 2025 version is for tax years ending on or after December 31, 2025. The supplied form does not give detailed rules for determining which businesses must file.
What you'll need
Have the following information ready to complete the schedule:
- Names and FEINs for the designated agent, the prior year's agent if different, the controlling corporation, and group members.
- The group's common year ending and each member's year ending, status, apportionment method, and member type.
- Names, FEINs, and dates for mergers and member sales requested in Step 1.
- The number of excluded members, plus their names, FEINs, and reasons for exclusion for Step 5.
- Income, deductions, Illinois additions and subtractions, and sales everywhere and inside Illinois for the calculations in Steps 2 through 4.
Attach explanations of eliminations and adjustments between members in Steps 2 and 3. Complete a separate Subgroup Schedule for each insurance company, financial organization, regulated exchange, and transportation company subgroup.
How to file
Attach Schedule UB to your Form IL-1120, Form IL-1120-ST, or Form IL-1065.
Complete the schedule in this order:
- Provide membership information.
- Figure federal taxable income.
- Figure combined business income.
- Figure the apportionment factor.
- Provide affiliated company information if Step 1, Section D reports one or more excluded members.
The form directs you to read the specific instructions before completing Step 2 and to consult the Schedule UB instructions for completing your main return afterward. Those instructions were not supplied here. The supplied text gives no mailing address or e-file directions.
Common mistakes
- Skipping Step 5 when members are excluded. Step 1 says to complete Step 5 if the excluded-member count is one or greater.
- Leaving out explanations for adjustments. Steps 2 and 3 call for attached explanations of eliminations and adjustments between members.
- Missing required subgroup calculations. Step 4 calls for separate Subgroup Schedules for the listed types of subgroups.
- Stopping before the loss-allocation lines. If Step 4, Column D, Line 10 is negative, complete Lines 11 through 13.
The form warns that failing to provide required information could result in a penalty.
Questions people ask
Where do I report members who left the group?
Step 1, Section C is labeled for members who left during the tax year. It requests the sold member's name and FEIN, the buyer's name and FEIN, and the sale date.
What reasons for excluding an affiliated company appear on the form?
Step 5 offers two choices: “80/20 company” and “not unitary.” Check one reason for each listed company.
How should I round the apportionment factor?
Step 4, Line 4 says to round to six decimal places. The loss-allocation ratio on Line 12 also uses six decimal places.
What if the controlling corporation belongs to the unitary group?
Check the box in Step 1 indicating that the controlling corporation is a member of the group.