The disclosure question probably depends on your state but practically speaking nobody is going to hand that over voluntarily, it is on you to ask every single time. I have a checklist I run before I touch the numbers on anything above a four-unit and "is the management company a third party" is line two, right after the rent roll date. Learned that the hard way on a 24-unit in Columbus where the owner's wife ran the PM company and the fee was buried at 10% when everything else in Franklin County was running 5 to 5.5% at the time. Shaved about $38k off the adjusted NOI once I normalized it, which at a 7 cap is not a rounding error.
Your 12% figure, I would actually push back on that a little because even the inflated number might not capture the full picture. In my experience when a seller controls the management company the fee is sometimes the cleaner part, the real games are in the maintenance invoices, the landscaping contract, the snow removal, stuff that flows through the same related entity and never gets scrutinized because people focus on the management line. On that Columbus deal the normalized NOI dropped another $14k just from pulling three years of maintenance bills and seeing the same LLC name on half of them. Before you go back to your buyer I would request 24 to 36 months of actual bank statements and reconcile every expense line against who got paid, not just what the fee percentage says.
