CBT-160-P: Underpayment of Estimated NJ Partnership Tax (2025)
New Jersey · NJ Division of Taxation · Used for tax years 2025
Form CBT-160-P helps partnerships determine whether they paid enough estimated New Jersey partnership tax and calculate any interest due on underpayments. It also documents exceptions to the underpayment interest charge and is attached to Form NJ-CBT-1065 when used to calculate i
Who files this form
Partnerships use CBT-160-P to determine whether they paid enough estimated New Jersey partnership tax and whether they owe interest on an underpayment.
Attach CBT-160-P to Form NJ-CBT-1065 if you use it to calculate underpayment interest or to show that you qualify for an exception.
When it's due
For the 2025 tax year, the form lists estimated tax installment dates as the 15th day of:
- The fourth month of your tax period.
- The sixth month of your tax period.
- The ninth month of your tax period.
- The first month after your tax period closes.
For the 2025 interest calculation, line 15 uses the payment date or the 15th day of the fourth month after the tax year closes, whichever is earlier.
What you'll need
Have these items available to complete the form:
- Your partnership name and federal EIN.
- Your 2025 Form NJ-CBT-1065, including the tax amount on line 4.
- Your 2024 Form NJ-CBT-1065, including the tax amount on line 4.
- Amounts and dates of estimated tax payments and credits for each payment period.
- Prior-year return information if you claim Exception I, or tax information for the applicable months if you claim Exception II.
If you made more than one payment for an installment, attach a separate calculation for that installment.
How to file
- Complete Part I, lines 1 through 9, to check for an underpayment in each payment period. Enter the amount from line 4 of NJ-CBT-1065 on line 1.
- If line 9 shows an underpayment, complete Part II to see whether an exception applies for that period.
- If neither exception applies, complete Part III, lines 13 through 18, to calculate interest.
- Include the total interest from line 18 on line 5 of NJ-CBT-1065.
- Attach CBT-160-P to NJ-CBT-1065 when using it to calculate interest or claim an exception.
The supplied text does not give a mailing address or e-filing directions.
Common mistakes
- Skipping Part II when claiming an exception. The form says to complete Part II if you meet an exception for any quarter.
- Carrying forward too much overpayment. Line 7(b) allows only the overpayment on line 9 that exceeds the total of all earlier underpayments.
- Leaving out a separate payment calculation. Attach a separate calculation if you made more than one payment for an installment.
- Ignoring partial months or rate changes. A partial month counts as a full month for interest, and changes in the average predominant prime rate must be reflected in the calculation.
Questions people ask
Does an underpayment always mean interest is due?
No. You do not owe interest for a payment period if your payments were timely and totaled at least the amount required under either exception for that period.
What is Exception I?
It uses the facts and applicable law from the prior year's return, but the current year's tax rates. If the prior return covered less than a year, annualize taxable net income by dividing it by the number of whole months covered and multiplying by 12.
What is Exception II?
It applies when estimated tax paid is at least 90% of the tax calculated by annualizing tax for the permitted months before an installment date. The permitted periods vary by installment.
How is underpayment interest calculated?
Interest runs from the installment due date to the payment date or the original due date of the final return, whichever is earlier. The annual rate is 3% above the average predominant prime rate, applied for each month or part of a month. The Division publishes interest rates at this link.