Delaware vs Illinois
A tax calculator says the difference is $5,100 a year. Once you count what a dollar actually buys in each, Delaware is $5,245 ahead — $52,447 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 · $52,447 over 10 years
You need 8.0% more for the move to break even.
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: Delaware 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 Delaware or Illinois
States that sit near Illinois on prices compared against Delaware, and the mirror of that. The comparison you would run next.
- Delaware vs Nevada— Nevada by $4,915
- Arizona vs Delaware— Arizona by $2,269
- Delaware vs Utah— Utah by $2,268
- Illinois vs Nevada— Nevada by $10,160
- Illinois vs Utah— Utah by $7,512
- Arizona vs Illinois— Arizona by $7,513
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.
- Sussex County, Delaware— 0.33%, the cheapest
- New Castle County, Delaware— 0.74%, the dearest
- Pulaski County, Illinois— 0.82%, the cheapest
- Lake County, Illinois— 2.68%, the dearest
Similar in price to Delaware
States that sit next to Delaware on the price index — often the comparison people should have run.
- Arizona— 100.7 on prices
- Nevada— 100 on prices
- Utah— 98.9 on prices
- Minnesota— 98.6 on prices
- Every Delaware comparison— all 50
- Every Illinois comparison— all 50
- The nine states with no income tax— and what they charge instead
Delaware and Illinois cost almost exactly the same, so this one really is about tax
Most comparisons on this site end up decided by the price level rather than the tax code. This pair is the exception: Delaware indexes at 99.8 and Illinois at 100 on the Bureau of Economic Analysis price index — 0.2 points apart, which is close enough that the deflator barely changes anything.
So the tax difference survives into the answer almost intact. Take-home differs by $5,100 and purchasing power by $5,245 — Delaware ahead either way, which is unusual enough to be worth stating. When someone tells you tax rates decide where you should live, this is the shape of pair they are imagining — 281 of the 1,275, so a little over one in five.
Where the two sit nationally: Illinois is the 18th most expensive place to live of the 51 — the 50 states and the District of Columbia — and Delaware is 20th. Housing, the component that moves most, is 102 against 93.9.
Grey columns are what a year of Delaware 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
Five separate taxes, and on this pair property tax is the biggest single difference — $5,554 against $454 for the income tax everybody quotes:
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 — $5,259 in Delaware, $4,805 in Illinois. A difference of $454.
Property tax — $1,832 in Delaware, $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 Delaware and Illinois keep income tax at the state level only, so the figures above are complete rather than approximations.
Total: $27,911 in Delaware against $33,011 in Illinois — 27.9% and 33.0% of gross.
And Delaware housing costs 8.6% more
These two states cost almost the same to live in, which is why the tax difference survives into the answer. The index is the Bureau of Economic Analysis Regional Price Parity — official, published per state, 100 is the national average — and it is worth looking at the components even when the headline barely moves, because they can disagree with it.
Cheaper in Illinois than DelawareDearer in Illinois than Delaware
Each bar is how far apart Delaware 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 — 99.8 in Delaware, 100 in Illinois. A gap of 0.2 points.
Housing — 102 against 93.9. A gap of 8.1 points, 40.5× the headline gap. This is what people mean when they say somewhere is expensive.
Goods — 96.2 against 103.8, 7.6 points apart — wide for goods: across all 1,275 state pairs the median goods gap is 2.7 points against 24.9 for housing, so on this pair the shopping basket genuinely differs and not just the rent.
Utilities — 103.8 against 85. 18.8 points apart, close enough not to change a decision.
Which half of this reaches you depends on whether you buy. Renting, the real difference between Delaware and Illinois is $306 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 $5,245. So buying widens the gap by $4,939: the more house you own, the more this comparison is worth to you.
The number to take into a salary negotiation: $108,019
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 Delaware?
$108,019. That is 8.0% more than you earn now. Anything less than $108,019 and the move costs you money however it is presented.
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 obvious shortcut fails here, and by a measurable amount. Scaling your salary by the ratio of price levels — $100,000 × 100/99.8 — gives $100,200. The answer is $108,019, so the shortcut is $7,819 too low: brackets, the Social Security ceiling and a property tax that ignores income all bend the line the shortcut assumes is straight.
The figure belongs to the two states and your income. On $40,000 the match in Illinois is $47,836, 19.6% above what you earn; on $250,000 it is $254,874, 1.9% above. The relationship bends by 17.6% across that range.
"Delaware" and "Illinois" are not places you can compare
Every figure above uses each state's median local property tax rate — its counties in Delaware, its counties in Illinois — and that is a simplification the page should own rather than hide.
Illinois has 102 counties, and the effective property tax rate runs from 0.82% in Pulaski County to 2.68% in Lake County — 3.2 times. On a $400,000 home that is a spread of $7,409 a year, without leaving the state.
102 counties. Each dot is one. The spread is 3.2 times from end to end, which is why a state average is not a number you can plan with.
Delaware has 3 counties, and the effective property tax rate runs from 0.33% in Sussex County to 0.74% in New Castle County — 2.2 times. On a $400,000 home that is a spread of $1,639 a year, without leaving the state.
So the honest version of this question is not "Delaware or Illinois" but which county. Picking the cheapest county in Illinois against the dearest county in Delaware swings the property tax line by $334 a year; the reverse choice swings it $9,382 the other way. Against a headline difference of $5,245, the county is not a detail — it is most of the decision.
Neither Delaware nor Illinois lets its counties levy their own income tax, so that layer is genuinely zero here rather than unmodelled — one of the 1,225 pairs out of 1,275 where it does not apply. It is the reason Delaware and Illinois are easier to compare honestly than most neighbours are.
Over 10 years: $52,447
Nobody moves for one year, and almost no comparison prices the decision over the horizon on which it is actually made.
At $5,245 a year of real difference, 10 years in Delaware instead of Illinois is worth $52,447 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 3 for the move to pay for itself. That is the figure a per-year comparison hides.
The first slice of it is not yours, though. Reckoning $15,000 for removal, fees and selling costs — this page's assumption, not a sourced figure — at $5,245 a year it takes 2.9 years to earn back, so a stay shorter than that loses money on a move the annual figure calls a win.
At three horizons: $15,734 over three years, $52,447 over 10, $157,340 over thirty.
None of those figures contains the one variable that could overturn them: the same job rarely pays the same in Delaware and Illinois. That is what the $108,019 break-even above is for — it prices an offer instead of assuming the offer is identical.
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 Delaware or Illinois?
- Delaware, by $5,245 a year in real purchasing power on $100,000 with a $400,000 home. The take-home difference is only $5,100; the rest comes from the cost of living, where Delaware indexes at 99.8 and Illinois at 100 against a national average of 100.
- How much do I need to earn in Illinois to match $100,000 in Delaware?
- $108,019 — 8.0% more. That accounts for federal tax, FICA, state tax, property tax and the price level in each state.
- What are the taxes in Delaware vs Illinois?
- On $100,000: state income tax of $5,259 in Delaware against $4,805 in Illinois, and property tax of $1,832 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?
- $52,447 in today's purchasing power, at $5,245 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.