In Maryland, where most of my rental properties are, there's a "protest period," after they raise your real estate tax assessment, and during that period you can submit an objection along with proof that your property is worth less than the assessment.
I've never objected to an assessment (although I wish I had, with some of the ridiculous assessments I'm straddled with), so I don't know how aggressively they fight you on these.
Hacking through red tape is no fun, and assessment offices know it, so my sense is that most simply make it as much of a hassle to fight them as possible, instead of playing traditional hardball.
Best of luck... you'll probably need it.
Cheers,
________________________
Brian
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