80-320: Interest and Penalty Worksheet (2024)
Mississippi · Mississippi DOR · Used for tax years 2024
Mississippi Form 80-320 is a worksheet for calculating 2024 individual income tax interest and penalties. It calculates interest on underpaid estimated tax, late filing and late payment charges, and the first-time home buyer penalty for resident and nonresident or part-year resid
Who files this form
Use Form 80-320 if your 2024 Mississippi income tax liability exceeds $200 to calculate interest on underpaid estimated tax.
The worksheet is also used to calculate first-time home buyer penalties, late filing penalties, and late payment interest and penalties for:
- Resident returns, Form 80-105.
- Non-Resident/Part-Year Resident returns, Form 80-205.
If your 2024 Mississippi income tax liability is $200 or less, the line 1 instructions say not to complete the rest of the worksheet. No interest is due on underpaid estimated tax.
When it's due
The worksheet lists these estimated tax payment due dates for tax year 2024:
- April 15, 2024.
- June 15, 2024.
- September 15, 2024.
- January 15, 2025.
For the 2024 return, the instructions identify April 15 as the original return due date used to calculate late payment interest and penalties, and October 15 as the extension due date used to calculate the late filing penalty. Those instructions do not print a calendar year beside these two dates.
What you'll need
Have these forms and records available, as applicable:
- Your 2024 Mississippi return: Form 80-105, line 20, or Form 80-205, line 22, for your net income tax liability.
- Your 2023 Mississippi return: Form 80-105, line 21, or Form 80-205, line 23, for your prior-year net income tax liability.
- Your 2024 balance due: Form 80-105, line 35, or Form 80-205, line 36.
- Payment records: income tax withheld, prior-year overpayment, and estimated tax paid as of each payment due date.
- Form 80-108, Part V, Schedule N, line 2: if calculating the first-time home buyer penalty. The worksheet refers to Form 80-100, the instruction booklet, for more details.
The worksheet also asks for your name, Social Security number, mailing address, county code, and spouse information where applicable.
Common mistakes
- Putting withholding in more than one column: the worksheet says to enter income tax withheld in column A only.
- Missing a carryforward: carry the overpayment or underpayment from line 8 into line 7 of the following column. Show overpayments as negative amounts and underpayments as positive amounts.
- Calculating interest on a negative underestimate: if line 8 is negative, enter zero on line 10.
- Leaving out an explanation: if filing requirements were met after a payment due date, the instructions say to compute interest in the applicable columns and provide an explanation.
- Not transferring the total: enter line 19's total on Form 80-105, line 36, or Form 80-205, line 37.
Questions people ask
How is interest on underpaid estimated tax calculated?
The worksheet uses interest of 1/2% per month, from the payment due date until the amount is paid or the next payment due date, whichever is earlier. Add the interest from columns A through D on line 11.
What is the late filing penalty?
The penalty is 5% per month on the net tax due, starting from the extension due date listed in the instructions. It cannot exceed 25% in total, and the instructions state a minimum penalty of $100.
What are the late payment charges?
Late payment interest is 1/2% per month on the tax due. The late payment penalty is also 1/2% per month, capped at 25% in total. Both run from the original return due date listed in the instructions.
What is the first-time home buyer penalty?
Line 12 applies a 10% penalty for withdrawals for unqualified expenses, using the amount from Form 80-108, Part V, Schedule N, line 2.
How do I calculate the worksheet's final total?
Add line 11, line 12, line 14, and line 18. Enter the result on line 19 and on Form 80-105, line 36, or Form 80-205, line 37.