Iowa's Tax Cut Just Rewrote The Dakota Dunes Math

For twenty years, the pitch across the bridge was simple. Buy in Dakota Dunes, keep your Sioux City job, and stop paying Iowa income tax on every paycheck. It was the kind of math that sold itself. South Dakota had no state income tax. Iowa's top rate sat above 8 percent. The decision practically made itself before a buyer ever toured a floor plan.

That math still gets repeated at open houses and in Facebook groups today. It is also, as of the 2026 tax year, mostly out of date.

The Number Everyone Still Quotes

Iowa's top individual income tax rate was 8.53 percent as recently as 2022. That figure shows up in almost every comparison of Sioux City to Dakota Dunes written in the last decade, and it is the number that made the cross-river move look like an obvious win for anyone earning a solid income.

Iowa did not sit still. Lawmakers phased the rate down year over year: 6 percent in 2023, a flat 4.82 percent in 2024, and a flat 3.8 percent starting with the 2025 tax year. The Iowa Department of Revenue confirmed in its official 2026 rate announcement that the flat 3.8 percent rate holds for this tax year as well, applying to every dollar of taxable income regardless of how much a household earns. There are no more brackets to climb through.

South Dakota's rate has not moved, because it was never there to begin with. The state has no individual income tax and no corporate income tax, a structural fact that predates Dakota Dunes itself.

So the gap did not close because South Dakota gave anything up. It closed because Iowa gave up most of what used to separate the two sides of the river.

The property tax line matters more now than it used to, because it is one of the few places the two states still meaningfully differ. Iowa's effective rate runs close to a third of a percentage point higher than South Dakota's on a typical home. That is real money over the life of a mortgage, but it is a different conversation than the one families used to have about their paychecks.

What Didn't Change, And What Quietly Also Changed

South Dakota still charges no personal income tax, no corporate income tax, no personal property tax, and no business inventory tax. Those are the structural pillars that made Dakota Dunes attractive to businesses relocating from the Iowa side in the first place, and none of them have moved.

What has changed is that Iowa closed off another classic argument for crossing the river: retirement income. Since 2023, Iowa has exempted most retirement income from state tax, including Social Security, pensions, and IRA and 401(k) distributions. A retiree living in Sioux City on those income sources now owes little or nothing in state income tax, the same outcome they would get living in Dakota Dunes. The move that used to be pitched heavily to retirees drawing down retirement accounts has lost one of its strongest selling points.

Iowa also eliminated its estate tax back in 2022 and phased its inheritance tax down to zero by January 1, 2025. Families weighing a move for legacy and estate planning reasons are working with a narrower gap there too.

None of this means South Dakota stopped being a lower-tax state overall. The Tax Foundation's 2026 State Tax Competitiveness Index still ranks South Dakota second in the nation, while Iowa has climbed to 17th, up from 44th six years ago. Iowa closed distance. It did not catch up.

A Bridge Finished Building While The Tax Code Was Catching Up

While Iowa's legislature was phasing down income tax rates, Sioux City and Dakota Dunes were finishing a different kind of connection. The Cloverleaf Crossing pedestrian bridge over the Big Sioux River opened in May 2026, linking Sioux City's 40 miles of trails to Dakota Dunes' 10 miles. The project took two decades to get from vision to ribbon cutting, delayed by flooding and a permitting dispute with the Army Corps of Engineers before finally opening this spring, funded entirely through local donors at a cost of $2.9 million.

The timing is worth sitting with. For years, the case for Dakota Dunes was framed almost entirely in tax terms, a financial argument made across a river you'd have to drive over to experience. Now there's a walking and biking connection tying the daily life of the two communities together just as the tax argument between them gets thinner. The physical case for living close to both sides is getting stronger at the exact moment the financial case for picking one side over the other is getting weaker.

The Business Park Still Making The Old Argument Out Loud

Not everyone has gotten the memo that the math shifted. In July 2026, construction broke ground on a new business park at the corner of Two Rivers Drive and Cottonwood Drive in Dakota Dunes, built by the local firm Koskovich and Murphy. Project manager Paul Koskovich explained the appeal in terms that would have sounded just as familiar in 2015 as they do now.

"Super good tax incentives here in South Dakota as compared to across the river."

He's not wrong about the business side of the ledger. South Dakota's no corporate income tax and no business inventory tax structure still gives commercial builders a real reason to choose the Dakota Dunes side of the interstate over the Sioux City side, and that calculation hasn't been touched by anything Iowa's legislature has done. The first building planned for the site runs 120 by 500 feet, with additional buildings proposed in the 60,000 to 100,000 square foot range as the development continues.

The irony is that Dakota Dunes itself was built by Berkshire Hathaway Energy, a company headquartered in Des Moines, Iowa. The same state whose income tax rate used to send residents looking for an exit built the exit.

Who The Math Still Favors

Business owners and commercial developers still have a clear, structural reason to prefer the South Dakota side, since none of Iowa's individual income tax reform touches corporate tax or business property tax at all.

Households comparing pure take-home pay on a W-2 salary are working with a much smaller gap than they were three years ago, closer to a few percentage points than the double-digit spread that used to define the conversation.

Retirees drawing Social Security, pensions, or retirement account distributions now see similar treatment on both sides of the river, since Iowa exempted most of that income starting in 2023.

Anyone weighing the decision purely on property tax will find a modest, real difference favoring South Dakota, but one that should be weighed against home price, insurance, and total cost of ownership on each side rather than treated as the whole answer.

A Few Questions Worth Asking Before You Decide

Does buying in Dakota Dunes still mean paying zero state income tax? Yes. South Dakota's lack of an individual income tax hasn't changed. What changed is how much Iowa charges on the other side of that comparison.

Is the property tax gap enough to justify the move on its own? It's real, but modest, roughly a third of a percentage point on effective rate. Most buyers will want to weigh it alongside home price, insurance costs, and commute rather than treat it as a standalone deciding factor.

Should I get tax advice before making this decision based on income or residency? Yes. This piece describes the general shape of state tax policy as of the 2026 tax year, not a specific household's liability. A CPA who knows both Iowa and South Dakota residency rules can walk through your actual numbers.

The tax story that used to sell Dakota Dunes on its own is a smaller part of the picture than it used to be. What's left is a genuinely nice place to live, with a golf course built by Arnold Palmer's design team, a growing business park, and a brand new bridge that makes it easier than ever to live near both sides of the river regardless of which one you choose. If you're weighing a move across the state line, or staying put in Sioux City and want the full picture of what your money buys on either side, The Vakulskas Group works both markets every day and can walk you through the current numbers, not the ones from three tax years ago.