Connecticut vs Illinois
A tax calculator says the difference is $18 a year. Once you count what a dollar actually buys in each, Illinois is $2,310 ahead — $23,102 over 10 years.
Property tax is set by counties, not states. Inside Texas alone the rate varies six times over, so this is the single choice that changes the answer most.
Does it work everywhere in Illinois?
in what the money buys · $23,102 over 10 years
A pay cut of up to $3,532 (3.5%) still leaves you level.
Who worked this out, and what it is built on
I build and maintain every comparison on this site — 1275 state pairs so far, on the same engine that runs the tax calculators for all 50 states and 3,143 counties. This is not a template with two names swapped into it: Connecticut and Illinois are run through the actual rules of each place, and if the numbers say the move is not worth it, that is what the page says.
Four sources, and one deliberate refusal. Federal figures from the IRS revenue procedure. State rates read one state at a time off each state’s own department of revenue. County property tax from the US Census Bureau. Cost of living from the Bureau of Economic Analysis Regional Price Parities, 2024 — and not from Numbeo or any other crowd-sourced index, because those are filled in by users, publish no methodology, and cannot be cited. That single choice is most of why the cost-of-living numbers here differ from everybody else’s.
When I get something wrong I publish the correction with the date and what it cost — including the two mistakes on these pages I found myself. Data last verified September 1, 2026.
Where to go from here
Almost nobody is choosing between exactly two places. These are the questions that usually come next, with the answer already attached so you can see which is worth opening.
Other moves involving Connecticut or Illinois
States that sit near Illinois on prices compared against Connecticut, and the mirror of that. The comparison you would run next.
- Connecticut vs Nevada— Nevada by $12,470
- Connecticut vs Delaware— Delaware by $7,555
- Arizona vs Connecticut— Arizona by $9,724
- Florida vs Illinois— Florida by $6,736
- Illinois vs Oregon— Illinois by $269
- Colorado vs Illinois— Colorado by $4,733
Each state on its own
The full detail behind each half of the comparison above.
The counties that decide it
Property tax is set by county, and the spread inside one state beats most state pairs.
- Windham County, Connecticut— 1.54%, the cheapest
- Hartford County, Connecticut— 2.13%, the dearest
- Pulaski County, Illinois— 0.82%, the cheapest
- Lake County, Illinois— 2.68%, the dearest
Similar in price to Connecticut
States that sit next to Connecticut on the price index — often the comparison people should have run.
- Massachusetts— 105.8 on prices
- Maryland— 105 on prices
- New Hampshire— 104.2 on prices
- Florida— 103.4 on prices
- Every Connecticut comparison— all 50
- Every Illinois comparison— all 50
- The nine states with no income tax— and what they charge instead
Connecticut or Illinois is a housing decision: Connecticut housing runs 24.6% dearer
The tax difference between Connecticut and Illinois is real but it is not what decides this one. On $100,000 with a $400,000 home, take-home moves by $18 a year. Housing moves by far more: the housing component of the official price index is 117 in Connecticut against 93.9 in Illinois, a gap of 23.1 points against just 3.6 on the index as a whole.
Which means a single blended cost-of-living number would hide the only variable that matters here. Put the housing gap into the arithmetic and Illinois comes out $2,310 a year ahead in what the money buys — $23,102 over 10 years. If you rent a small flat, most of that advantage never reaches you; if you buy a family house, it is understated.
Where the two sit nationally: Connecticut is the 10th most expensive place to live of the 51 — the 50 states and the District of Columbia — and Illinois is 18th. Housing, the component that moves most, is 117 against 93.9.
Grey columns are what a year of Connecticut and a year of Illinois are worth in the same money. The bars between them are each thing that changes, in the order it changes: green adds, amber takes away.
Where the money actually goes, line by line
Before the layers, the conclusion they lead to: on this pair the tax code is a side issue. The price level moves the answer 12.4 times more than the largest single tax difference between Connecticut and Illinois. The five layers still deserve walking, because they are what people arrive believing decides it:
| Connecticut | Illinois | |
|---|---|---|
| Gross salaryThe same on both sides, by construction | $100,000 | $100,000 |
| Federal income taxSet in Washington, identical in every state | $13,170 | $13,170 |
| Social Security and MedicareAlso federal, also identical | $7,650 | $7,650 |
| State income tax | $4,975 | $4,805 |
| Property tax on a $400,000 homeAt each state's median local rate | $7,198 | $7,386 |
| All tax | $32,993 | $33,011 |
| Effective rate on gross | 33.0% | 33.0% |
| Take-home | $67,007 | $66,989 |
| Price level, all items (BEA, US = 100)What a dollar actually buys there | 103.6 | 100.0 |
| Price level, housingThe component that decides most moves | 117.0 | 93.9 |
| Take-home, adjusted for pricesThe only line that can be compared directly | $64,679 | $66,989 |
Federal income tax — $13,170 either way. Identical, because it is federal. Any comparison that shows a difference here is wrong.
FICA — $7,650 either way. Also federal, also identical.
State income tax — $4,975 in Connecticut, $4,805 in Illinois. A difference of $170.
Property tax — $7,198 in Connecticut, $7,386 in Illinois on a $400,000 home, at each state's median local rate. This is bigger than the income tax difference, and it runs the other way — which is the whole reason the headline number disappoints.
Local income tax — zero on both sides. Both Connecticut and Illinois keep income tax at the state level only, so the figures above are complete rather than approximations.
Total: $32,993 in Connecticut against $33,011 in Illinois — 33.0% and 33.0% of gross.
And Connecticut housing costs 24.6% more
The cost of living gap between Connecticut and Illinois is almost entirely a housing gap, and that is only visible because the Bureau of Economic Analysis Regional Price Parity publishes its components separately rather than as one blended number. 100 is the national average.
Cheaper in Illinois than ConnecticutDearer in Illinois than Connecticut
Each bar is how far apart Connecticut and Illinois are on that component, and which way. Housing almost always runs several times wider than everything else — which is why a single blended index tells you very little.
All items — 103.6 in Connecticut, 100 in Illinois. A gap of 3.6 points.
Housing — 117 against 93.9. A gap of 23.1 points, 6.4× the headline gap. This is what people mean when they say somewhere is expensive.
Goods — 97.3 against 103.8, 6.5 points apart — 3.6 times narrower than the housing gap — and typical: across all 1,275 pairs the median is 2.7 points for goods against 24.9 for housing. Blended into one figure, what you are reading is mostly housing wearing a general label.
Utilities — 146.5 against 85. 61.5 points, the second widest component after housing on this pair, and large enough to matter to anyone heating or cooling a big house.
Which half of this reaches you depends on whether you buy. Renting, the real difference between Connecticut and Illinois is $2,748 a year — property tax comes out of your side entirely, and what is left is the price level. Buying a $400,000 home it is $2,310. So renting is where the gap is widest here, by $438 — unusual, and it means buying erodes the advantage rather than compounding it.
The number to take into a salary negotiation: $96,468
This is the question people are actually asking and almost nobody answers: what would I need to earn in Illinois to live exactly as well as I do on $100,000 in Connecticut?
$96,468. That is 3.5% less than you earn now. You could take a pay cut of $3,532 moving to Illinois and be no worse off — which is a very different conversation to have with a recruiter than "Illinois has lower taxes".
The dashed line is the salary you earn now. The solid line is what matches it in Illinois. If the relationship were a simple multiplier the two would be parallel — they are not, because brackets, the Social Security ceiling and a property tax that does not move with income all bend it.
The shortcut happens to land here: scaling by the ratio of price levels gives $96,525 against a true $96,468, $57 apart. A coincidence of these two price levels at this salary rather than a rule — on most of the other 1,274 pairs the same shortcut is out by thousands.
The figure belongs to the two states and your income. On $40,000 the match in Illinois is $39,907, 0.2% below what you earn; on $250,000 it is $235,895, 5.6% below. The relationship bends by 5.4% across that range.
Over 10 years: $23,102
At $2,310 a year, 10 years in Illinois comes to $23,102 — and the county choice inside Illinois is worth $74,092 over the same period. Both are real; only one of them is in the headline.
At $2,310 a year of real difference, 10 years in Illinois instead of Connecticut is worth $23,102 in today's purchasing power — before compounding anything you might invest it in.
The line starts below zero because moving costs about $15,000 and lands entirely in year one. It takes until year 7 for the move to pay for itself. That is the figure a per-year comparison hides.
And it is slower to arrive than the annual figure suggests. Reckoning $15,000 for removal, fees and the cost of selling — an assumption this page makes, not a figure from a source — at $2,310 a year it takes 6.5 years to recover — so the annual figure only becomes yours from year 8.
At three horizons: $6,931 over three years, $23,102 over 10, $69,307 over thirty — and the three-year figure does not clear the cost of getting there.
None of those figures contains the one variable that could overturn them: the same job rarely pays the same in Connecticut and Illinois. That is what the $96,468 break-even above is for — it prices an offer instead of assuming the offer is identical.
Choosing the county matters more than choosing the state here
This comparison is worth $2,310 a year. Choosing where inside Illinois to live is worth $7,409 a year on the same $400,000 home — 3.2 times as much.
Illinois has 102 counties and the effective property tax rate runs from 0.82% in Pulaski County to 2.68% in Lake County. Move to the wrong county in the better state and you have given back more than the move gained you, twice over.
Which reframes the question. Rather than "Connecticut or Illinois", the decision that carries the money is which county inside Illinois — and the answer is not visible on any comparison that stops at the state line. Set both in the calculator above and every figure on this page recomputes on your actual rates rather than two medians.
The same logic applies to the losing side: Connecticut has counties cheaper than the median used here too, and for a reader who is staying put, moving county at home may be the better version of this decision.
You could take a $3,532 pay cut to move to Illinois and be no worse off
That is the version of this comparison worth taking into a negotiation, and it is not a figure any tax calculator produces.
Matching your $100,000 standard of living in Connecticut takes $96,468 in Illinois — 3.5% less than you earn now. So an offer of $96,468 is not a downgrade, and an offer above it is a raise however it looks on paper.
The reverse framing is the one recruiters use, and it is worth being able to answer: a company in Connecticut offering to match your current salary is offering you less than the Illinois job at $96,468. On 10 years the difference is $23,102.
Where every number here comes from
Four sources, each read off the body that publishes it:
US Bureau of Economic Analysis — Regional Price Parities by State and Metro Area, 2024 (released 19 February 2026) — read 2026-09-08. https://www.bea.gov/data/prices-inflation/regional-price-parities-state-and-metro-area
IRS — Revenue Procedure for the tax year (federal brackets, standard deduction and FICA) — read 2026-09-02. https://www.irs.gov/
Each state's own department of revenue (state income tax rates and deductions), verified one state at a time — read 2026-09-02. https://estimatetax.net/sources/
US Census Bureau, American Community Survey (county effective property tax rates) — read 2026-08-31. https://data.census.gov/
The cost of living index is the part worth checking, because it is where comparison sites usually reach for something crowd-sourced. The Regional Price Parities are produced by the Bureau of Economic Analysis, cover every state and metro area, and are published with a methodology document. The figures here are the 2024 release and are not extrapolated forward.
And what this page does not model:
— The cost of living index is the BEA's Regional Price Parity for 2024, the most recent published. It is not extrapolated to the current year, and it is a state-wide average — inside a state, a metro area and a rural county differ by more than most state pairs do.
— Moving costs, state transfer taxes on buying a home, and the cost of selling the one you have are not included. On a short stay they can outweigh every annual difference on this page.
— Sales tax is not modelled. It is inside the BEA index — that is what a price parity measures — but it is not broken out separately here.
— The comparison assumes the same salary in both places unless you change it. In practice a job in a high-cost state usually pays more, which is exactly what the break-even figure is for.
— Health insurance, childcare and car insurance vary enormously by state and are only inside the index as averages. If any of the three is a large part of your budget, it deserves its own arithmetic.
Where to go next
Questions
- Is it cheaper to live in Connecticut or Illinois?
- Illinois, by $2,310 a year in real purchasing power on $100,000 with a $400,000 home. The take-home difference is only $18; the rest comes from the cost of living, where Connecticut indexes at 103.6 and Illinois at 100 against a national average of 100.
- How much do I need to earn in Illinois to match $100,000 in Connecticut?
- $96,468 — 3.5% less than you earn now, so a pay cut of up to $3,532 still leaves you level. That accounts for federal tax, FICA, state tax, property tax and the price level in each state.
- What are the taxes in Connecticut vs Illinois?
- On $100,000: state income tax of $4,975 in Connecticut against $4,805 in Illinois, and property tax of $7,198 against $7,386 on a $400,000 home at median county rates. Federal tax and FICA are identical in both — $13,170 and $7,650 — so any comparison showing a difference there is wrong.
- Does Illinois really have lower property tax?
- That depends entirely on the county, which is why a state-level answer is not much use. Illinois runs from 0.82% in Pulaski County to 2.68% in Lake County — 3.2 times, or $7,409 a year on a $400,000 home. The median is 1.85%.
- How much is the difference over 10 years?
- $23,102 in today's purchasing power, at $2,310 a year. That excludes moving and housing transaction costs, which land in year one and can outweigh everything else on a short stay.
- Where does your cost of living data come from?
- The Bureau of Economic Analysis Regional Price Parities for 2024, an official index covering every state and metro area with a published methodology. Not a crowd-sourced database — and it comes broken into housing, goods, utilities and services, which matters because housing moves several times more than anything else.