Oakland County, Michigan property tax

ACS 5-year median real estate taxes paid (table B25103) divided by ACS 5-year median value of owner-occupied housing units (table B25077), county-wide. This is a ratio of two independently estimated medians — not the median of the ratio, and not a rate any parcel is billed. It reflects the actual mix of overlapping districts, exemptions and assessment caps as experienced by owner-occupants, and it lags: a 5-year sample centres about two and a half years before its end date.

Layer 1 of the county property-tax corpus: a MEASURED baseline from ACS 2020-2024 5-year, not a published rate. No statutory rate, assessment ratio or exemption has been collected for these counties yet, so nothing here should be read as what a particular property would be billed.

Three corrections to the usual account of Michigan, each checked against Treasury's own current documents. The exemption is "up to 18 mills", not 18 mills: 942 of 3,266 unit-and-district rows in the 2025 rate report show some other gap, mostly Headlee-rolled fractions just below 18. The Constitution CAPS the assessment proportion at 50% rather than setting it — the STC guide states the ceiling — and the General Property Tax Act is what fixes it there. And the personal-property carve-outs mean commercial personal property pays only 6 of the 18 while industrial personal pays none of them and no State Education Tax either, which the rate report confirms to four decimal places. The two caps are different instruments and must not be merged. Proposal A caps the VALUE of one parcel and uncaps it to state equalized value the year after a transfer; Headlee rolls back the MILLAGE of a whole jurisdiction, permanently and never upward. They share a multiplier in 2025 at 1.031 — Bulletin 14 of 2024 is explicit that no local unit may use any other figure, and that 1.05 does not enter the formula because 1.031 is lower — but they have NOT always agreed. The bulletin's own historical table gives 2023 as 1.050 capped value against 1.079 Headlee, and 2024 as 1.050 against 1.051. A model carrying one inflation number per year is wrong for both. CITATION HAZARD, and the worst in this corpus. Michigan's statute host is unusable by any automated client: www.legislature.mi.gov answers HTTP 200 with a 1021-byte CAPTCHA body — "User validation required to continue", error code 426, IP-scoped — for every URL on the host including .pdf paths, which come back as content-type text/html. It presents identically in a real browser. The alternate hostname legislature.michigan.gov fails TLS outright, with no matching certificate subject name. A status code cannot see any of this, and neither can a content assertion, because there is no document to assert against. So NO MCL citation appears in this record. Every figure is cited instead to michigan.gov, which gates a plain client at 403 but is otherwise well behaved: it returns real 404s for paths that do not exist, so existence stays checkable, and its documents restate the statutes with their section numbers. Section numbers named in the text above are therefore signposts, not citations — the operative evidence is the Treasury or State Tax Commission document beside them. That is a real tier cost, taken deliberately, rather than a fabricated statute URL.