Iowa is legally clean but limited by size.
The law and the data both work here. No legal obstacle, just a smaller market than the states we build first.
So Iowa decides these on market value, which means the evidence is recent sales of genuinely comparable homes. What matters is whether that whole set of sales sits below your assessed value. If those sales bracket your assessment rather than falling under it, boards generally sustain the assessor, because nothing's been clearly disproved.
Now a few things lose almost everywhere. Comparing your assessment to a neighbor's assessment usually isn't admissible where the argument is market value. One sale on its own can be dismissed as an outlier. And the size of your increase, or the size of your bill, isn't evidence about what your home is worth.
Deadlines here are set locally rather than by one statewide date, so the one that binds you is printed on your own assessment notice.
And that notice is really the thing to go find today. It's what starts your clock, it's usually a much shorter window than people expect, and there's no getting it back once it's gone.
So we only turn a state on after reading its appeal rules and its actual board decisions, so that what we tell somebody is right rather than generic. That takes a few days per state and it's honestly the reason our answers are worth anything.
In the meantime our free check runs in Washington, Illinois and Oregon. If you leave your email on the check page we'll write to you the day Iowa goes live, and not before.
Also, there's one move that has nothing to do with appealing and that a lot of people miss entirely. Most states take exemptions off your bill before any of the value arithmetic happens, starting with a homestead exemption if you actually live in the house, and usually extra ones for owners over 65, for veterans, and for people with disabilities. They're often worth more than an appeal win, they carry forward year after year rather than needing to be re-won, and plenty of people who qualify have never filed for them. Your county assessor's website lists what's available where you live, and it costs nothing to look.
We screened all fifty states and DC on the same two questions. Does winning a lower market value actually lower your bill, or is there a cap sitting in between? And can the evidence even be assembled from public records?
This comes from our own fifty-state screen, which checked each state's cap structure, whether sale prices are public, whether an assessment-based argument exists, and how many appeals actually get filed. Where we quote an appeal count it came from the state or county that published it. If you spot an error, please write to hello@propertytaxbuddy.com and we'll correct it and say what changed.