A recent thread here asked whether a cost segregation study really moves the needle or whether it's overhyped. The answers were all over the place. Most of the disagreement came down to one thing: people treating a deduction and tax savings as the same thing.

They aren't. A deduction lowers your taxable income. Your tax savings is how much that deduction actually takes off your tax bill. That depends on your tax bracket, and on whether you can even use the deduction this year.

Here's a simple example with round numbers. A cost seg study shows $100,000 of extra depreciation. That doesn't put $100,000 back in your pocket. In the 24% federal bracket, it saves closer to $24,000 in federal tax, plus whatever your state adds. If the loss is passive and you have no passive income or exception to use it against, it may just get suspended and carried forward. Some of the benefit can also come back as depreciation recapture when you sell.

None of that makes cost seg bad. It just means the headline number and the real number are different.

Have you ever been shown a big deduction and later found out the actual savings were much smaller? What happened?