October 1 is not just a date on a calendar
Every property in Connecticut gets a value stamped on it on October 1. Whatever your house is worth that day - on paper, in the assessor's file - is what you're taxed on for the entire grand list year that follows. Not what it sells for next spring. Not what a real estate agent would tell you it's worth. What the town says it's worth, as of that one date.
Most homeowners never think about this until they open a tax bill that feels wrong. By then the number is already locked in, and most people just pay it. That's the mistake. There's a real process to challenge an assessment you think is off, and I would say more Connecticut homeowners should use it than actually do.
Let me put it this way: nobody double-checks their assessment until the bill hurts. The ones who win an appeal are usually the ones who checked before it hurt.
Why your assessment isn't what you think it is
Here's where people get confused, and it's an honest mistake. Connecticut law requires towns to assess property at 70% of fair market value, not 100%. So if your assessment shows a number well below what you think your house would sell for, that's not necessarily wrong - it might just be the 70% rule doing what it's supposed to do. That assessed number is also the exact figure your town's mill rate gets applied to when your bill gets calculated, and that side of it is its own topic worth understanding.
Worth knowing: Compare your assessed value to 70% of what you believe your home would actually sell for today, not to the full market value. That's the real number to check against.
The confusion cuts the other way too. I showed up to a listing appointment once expecting a modest ranch - that's what the town card said. What I found on the lot was a large multi-story home, expanded over the years with none of it permitted or reported. The house on paper and the house in front of me were basically two different properties. Town records are not always accurate. Sometimes they're outdated, sometimes a past owner never reported work, sometimes the assessor's data just has an error in it. You won't know unless you look.
The window you actually have to appeal
This is the part most people get wrong, and it costs them a full year. You don't appeal in October. You appeal to your town's Board of Assessment Appeals (BAA), and the statutory deadline to file is February 20 of the following year - though a good number of towns extend that to March 20, especially in a revaluation year.
Basically, the process runs like this once you decide to challenge your assessment:
Before filing
- Get your assessment card from the town assessor's office and check it for errors - square footage, bedroom count, condition notes
- Pull a recent independent appraisal if you have one, or comparable sales for similar homes nearby
Filing the appeal
- Submit the BAA application form, available from your assessor's office or town website, by February 20 (or March 20 if your town extended it)
- Include your supporting evidence with the application, or bring it to the hearing - both work
After filing
- Hearings are generally held in March, or April if the town extended its deadline
- The board issues a decision after the hearing
Miss that filing deadline and you're not appealing this year's assessment. You're waiting for next year's grand list and starting over.
What actually convinces a board
A board isn't going to lower your assessment because you feel like your taxes are too high. Everybody feels that way. What moves the needle is evidence - a recent independent appraisal, real comparable sales on similar homes in your area, or a documented error in the town's own record of your property.
I mean, if the assessor's card lists square footage or a bedroom count that doesn't match your actual house, that's a straightforward correction. If your case is really about value - you think the number is too high relative to what similar homes have sold for - that's where comps do the work. Bring the sales. Not your opinion of what the house is worth.
If the board disagrees with you, there's one more step: you can appeal to Connecticut Superior Court, but only within two months of the date the board's decision notice is mailed. Miss that window and the right to challenge that year's assessment is gone - for good, not just for that hearing.
When this actually pays off - and when it doesn't
Assessment shocks show up hardest in revaluation years. Every town revalues on its own schedule, commonly every five years, and that's when a lot of homeowners open a new assessment and don't recognize the number. If your town just went through a revaluation and your bill jumped in a way that doesn't match what similar homes nearby are actually worth, that's exactly the situation this process exists for.
If you're in this situation right now, here's what I'd do: pull your assessment card before October 1 locks in this year's number, compare it against real comps - not Zillow, actual sold prices - and decide then whether it's worth the appeal in February. Don't wait until the tax bill arrives to start asking questions.
Bottom line: Check your assessment card before October 1, not after your tax bill shows up. If the number doesn't hold up against real comps or the record has an error, file with your Board of Assessment Appeals by February 20 - and don't miss it, because that door closes for the year.
Frequently Asked Questions
When is the deadline to appeal a Connecticut property tax assessment?
The statutory deadline to file with your local Board of Assessment Appeals is February 20 of the year following the October 1 assessment date. Many towns extend this to March 20, particularly in a revaluation year. Check with your town assessor's office to confirm which deadline applies to you.
Why is my assessed value so much lower than what my house is worth?
Connecticut law requires towns to assess property at 70% of fair market value, not 100%. A lower assessed number compared to what you think your home would sell for is often just the 70% rule working correctly - not a sign of an error.
What evidence do I need to win a property tax appeal in CT?
A recent independent appraisal, comparable sales data on similar homes in your area, or documentation of a factual error on your assessment card - wrong square footage, bedroom count, or condition notes. Opinions about your tax bill being too high don't move a board. Evidence does.
What happens if the Board of Assessment Appeals denies my appeal?
You can appeal further to Connecticut Superior Court, but you have to file within two months of the date the board's decision notice is mailed. Miss that window and you lose the right to challenge that year's assessment entirely.