The percentage model loses me money on 2-4 unit buildings

Your own numbers say the duplex is unprofitable at any price you're willing to charge. 2.1 hours per door per month is 4.2 hours on a duplex, times 34, is 143 in coordinator cost before overhead, rent, software or your time. If your overhead allocation is anything like typical you're at 200 plus on cost against 240 in revenue, so you're clearing 40 a month to carry the liability of someone else's building.

The weak spot in that arithmetic is that I've assumed 2.1 hours is flat across property types, and you said yourself the fixed per-building work is what breaks it. Split the average. Give me hours per building per month and hours per door per month separately, then price two line items instead of one blended number. My guess is you land on something like 140 per building plus 60 per door, which prices a duplex at 260 and a fourplex at 380, and both of those are defensible to an owner because you can show what each piece buys.

Before the pricing, check what your maintenance markup does to your license status. In a lot of states property management activity sits under the real estate license and marking up contractor work can be treated differently from collecting a management fee, and the rules genuinely differ state to state. My state commission publishes guidance on it and it took me an hour to read. That's a question for your broker of record or an attorney in your state rather than a forum, but I'd get the answer before the markup shows up on an owner statement.

As the owner on the other side of that invoice, I'd rather pay 275 flat and know the number than pay 10 percent and wonder what a vacancy month does to your attention. Percentage pricing always struck me as odd anyway, since your work goes up when the unit is empty and your fee goes to zero. Show me the two-line breakdown @ledger described and I'd sign it without much argument.

The repricing is a contract amendment, so look at the termination language before you send anything. Most management agreements I've read have a 30 day out for the owner and a longer one for the manager, which means a price increase letter is effectively an invitation to leave at the owner's convenience. If you're going to lose four owners anyway, do it on your schedule with a clean effective date and a signed amendment rather than a notice in the December statement. I'd also pin down who authorizes repairs and at what dollar threshold, because the 500 line in your markup should match the approval limit in the agreement or you'll have an argument about the first 600 job.

I pay 10 percent on a triplex and I'd pay your 275 without blinking, because the alternative is me driving to a water heater on a Tuesday. But I'd want the leasing fee explained. Going from half a month to a full month on a 1,200 unit is another 600 per turn, and if my tenants stay two years that's a real number against a service I can partly see myself. Price the management honestly and leave the leasing fee where it is. You'll lose fewer owners on a fee they pay monthly than on one that lands as a surprise at turnover.