CT-1120A: Corporation Business Tax Return Apportionment Computation (Revision 2025-12)
Connecticut · Connecticut DRS · Used for tax years 2025
Form CT-1120A calculates the Connecticut apportionment fractions used on the Corporation Business Tax Return, Form CT-1120. It reports Connecticut and everywhere receipts for net income apportionment and asset values for minimum tax base apportionment.
Who files this form
Complete and file Form CT-1120A as part of Form CT-1120, Corporation Business Tax Return, only if the company both:
- Carried on business within and outside Connecticut during the income year.
- Was taxable in another state during that year.
A corporation entitled to apportion its income must complete Schedule Q or an applicable special apportionment form. The form lists special rules for certain businesses, including air carriers, broadcasters, financial service companies, and motor bus and motor carrier companies.
What you'll need
Have the following information ready:
- Corporation name, Connecticut Tax Registration Number, and income-year beginning and ending dates.
- Connecticut and everywhere receipts for Schedule Q, including sales, services, rentals, leases, licenses, interest, and other receipts.
- Average monthly net book values for Schedule S, including cash, receivables, investments other than stock, inventories, depreciable assets, land, and other assets. Exclude holdings of stock of private, nongovernmental corporations.
- The corporation's pro rata share of partnership or joint venture receipts, if applicable.
Additional attachments apply in certain cases:
- Qualifying manufacturers electing the three-factor formula must attach a statement with the apportionment factor calculation.
- A taxpayer requesting an alternate apportionment method must provide a statement describing the specific alternate method and data supporting why the statutory method produces grossly inequitable results.
How to file
Electronically: File Form CT-1120A with Form CT-1120 using myconneCT. This service allows taxpayers to file, pay, and manage state tax responsibilities electronically.
By mail: Complete the form in blue or black ink only. Do not use staples. Submit the correct year's form to the Connecticut Department of Revenue Services as part of Form CT-1120. The supplied text does not give a mailing address.
When completing the calculations:
- Schedule Q: Add Lines 1 through 7 in each column. Divide Line 8, Column A, by Line 8, Column B, and carry the fraction to six places. Enter it on Form CT-1120, Schedule A, Line 2.
- Schedule S: Add Lines 1 and 2 in each column to get Line 3. Divide Line 3, Column A, by Line 3, Column B, and carry the fraction to six places. Enter it on Form CT-1120, Schedule B, Line 2.
Common mistakes
- Using the wrong year's form. Each form is year specific. Submit the correct year's form to prevent processing delays.
- Leaving the Everywhere column blank when claiming zero Connecticut apportionment. A figure must be entered for both Schedule Q and Schedule S.
- Including receipts from sales of property not held for sale in the ordinary course of business. These receipts must be excluded from Schedule Q.
- Including private corporate stock holdings in Schedule S. The asset calculation excludes stock of private, nongovernmental corporations.
- Using staples or the wrong ink for a mailed form. Use blue or black ink only, and do not staple.
Questions people ask
What method does Schedule Q use?
Corporations not subject to industry-specific apportionment methods must use a single receipts factor. Sales of services and intangible property use market-based sourcing rules.
When do service receipts count as Connecticut receipts?
Enter service receipts in the Connecticut column if and to the extent the service is used within Connecticut.
What if the corporation owns an interest in a partnership or joint venture?
Include the corporation's pro rata share of the partnership's or joint venture's receipts in both the numerator and denominator of the Connecticut statutory apportionment formula.
Can a corporation request a different apportionment method?
Yes, but it must initially file using the statutory method and pay the tax due on that basis. It must also submit a specific alternate method and supporting data showing that the statutory method produces grossly inequitable results. A different result under another method alone does not justify an exception. The Commissioner will notify the company whether the proposed method is accepted or rejected; if accepted, the tax will be adjusted.