Supplemental Motor Vehicle Tax

What is a Supplemental Motor Vehicle Tax bill?
A Supplemental Motor Vehicle Tax is a tax on motor vehicles newly registered between the dates of October 2, 2019 and July 31, 2020.

When is the supplemental tax due?
A Supplemental Motor Vehicle Tax is due in full, in one installment on January 1, 2021. As with all municipal taxes, you have until the first business day of the following month to pay your tax without interest.

How is the Supplemental Tax different from a motor vehicle tax that is due in July 2020?
The taxes due in July are for the vehicles that were registered to you as of October 1, 2019. A vehicle that was registered after October 1, 2019 is then put on a supplemental list to be billed the following January. A Supplemental motor vehicle tax is prorated from the month your vehicle is first registered through September 30, 2020. 

Why does my bill have two cars listed on it? One is my old car and one is my new car. I used the same plate when I registered my new car.
The registration plate is the key to a credit. Keep reading!

I paid taxes in July 2020 for a car I traded in last spring!  You said I had to pay the whole bill and I would get a credit on my new car! Where is it?
You should have a “credit vehicle” on your supplemental tax bill. The credit is not in actual dollars and cents, but in assessment value.  For example, let’s say on October 1, 2019 you had a vehicle registered that had an assessed value of 1000.  Your tax would be $45.00 with a mill rate of 45 and payable on July 1, 2020. In April of 2020 you traded in your 1000 value car for one with an assessed value of 4000. Your new car’s assessment would be pro-rated to cover April 2020 through September 30, 2020 at 50%, which would bring your new car’s assessment down to 2000 in value. Your old vehicle, which you already paid taxes on, would be pro-rated for the period of time that you did not own it, and that would be your assessment credit. Your 1000 valued vehicle would entitle you to a 50% credit of 500 assessment value towards your new car. Your new car’s net assessment, on which you would be taxed, would then be 1500. (Keep reading!)

New Car Assessment: 4000

Pro-rated New Car Assessment (From April 2020): 2000

Credit for Old Car: (500) 

Net Assessment: 1500 (Amount you pay tax on)


THIS IS CONFUSING!! Who made these rules and regulations? 

- It wasn’t us!                                 

Both the Assessor and the Collector are bound by the State of Connecticut Statutes. The Supplemental Motor Vehicle tax laws are found in Section 12-71b of the Connecticut State Statutes.

I moved out of this town last year and paid you taxes in July 2020 for my cars. Now you are sending me a bill for a car that we bought after we moved! How can you do that? We didn’t even own the car while we lived there!!

No, you didn’t, but the car that you transferred the plates from was taxed here on the October 1, 2019 Grand List. In order for you to receive the “credit” mentioned in the previous questions and answers, we must bill you for your new car. The Town that you live in now cannot give you credit for taxes paid to another town in July. Hopefully, this should be the last tax bill you get from us. If your cars are correctly registered in your new town as of October 1, 2020, then your new town will bill you in July 2021.

What happens if I don’t pay my taxes?

Well, we hope you will be able to pay your taxes in a timely manner, but if you don’t then we must charge interest at the rate of 18% per year on any outstanding tax. You will not be able to register any motor vehicle until all taxes assessed in your name are paid with either cash or credit card via our online payment portal for an immediate release; a check payment including personal, business, money order or a bank check will be a ten-business day wait. We will even send your account to a collection agency or use other collection procedures allowed in the statutes if needed. We cannot waive any accrued interest charges nor give you a release to the Department of Motor Vehicles until all your motor vehicle taxes are paid.

I am still confused. I don’t want to pay a bill that I don’t understand. How do I get more help?

We understand this is confusing, however, the Assessor and the Collector have been working with this for a long time, so we may understand why we are taxing you, but you may not. Please feel free to call and we will do our best to help you.

All ASSESSMENT Questions should go to the Assessor’s Office:

Phone: (860) 489-2222
Fax: (860) 496-5907
Hours:  Monday-Wednesday 8:30 am to 4:00 pm; Thursday 8:30 am to 6:30 pm & Friday 8:30 am to 12:30 pm

All TAX Questions should go to the Tax Collector’s Office:

Phone: (860) 489-2209 x6
Fax: (860) 496-5905
Hours: Monday - Wednesday 8:30 am to 4:00 pm; Thursday 8:30 am to 6:30 pm & Friday 8:30 am to 12:30 pm

Supplemental Motor Vehicle Tax Bills
Supplemental tax bills are issued pursuant to Section 12-71b of the General Statutes of the State of Connecticut and cover motor vehicles newly registered after October 1st, and before the following August 1st. Supplemental tax bills are due January 1st and must be paid in full on or before February 1st to avoid interest figured at 1.5% per month from January 1st subject to a minimum interest charge of $2.00 per tax bill.

                                                  CODES USED ON SUPPLEMENTAL BILLS

Month AcquiredNewly Acquired Vehicle CodeReplacement Vehicle Code Percentage# of Months Owned


12 Months


11 Months


10 Months


9 Months


8 Months


7 Months 


6 Months


5 Months


4 Months


3 Months


Purchased after October 1st and NOT REPLACING a vehicle appearing on the October 1st Grand List. ~Tax due will be for the number of months remaining in the assessment year including the month of registration.


Purchased after October 1st and before the following August 1st replacing a vehicle that appeared on the October 1st Grand List. The tax due in July for the vehicle on the October 1st Grand List must be paid in full. The tax due in January following the purchase on the replacement vehicle should show a credit for the October 1st replaced vehicle based on the codes applicable.


If the tax code on the tax bill is a Code N to Code W, the tax bill is due and payable to the municipality to which your July 1st tax was due regardless of your present residence.