There's a 20 percent rental cap in the HOA docs and my agent shrugged

Ask the HOA's management company for a written rental status letter before your inspection period ends, not the agent. What you want in writing: current count of leased homes, the cap number, whether there's a waitlist and how long it is. "Half the street is already rented" is exactly the answer that should worry you, because if they're at 22 of 18 allowed then someone eventually complains and the board starts enforcing.

The 12 month minimum is usually the easy part, most of my leases are 12 months anyway. The registration requirements are the annoying part, some associations want the lease on file and a fee per tenant turnover.

Grandfathering varies by how the declaration is written and by state law on amendments, so the only version that matters is what a lawyer tells you after reading your specific docs. Whether an HOA can force a tenant out or only fine the owner is the same story, don't take mine or the agent's word on it.

Underwriting angle nobody's mentioned yet: the cap follows you to the exit. If you ever want to sell to another investor, a maxed cap shrinks your buyer pool to owner-occupants, which can cost you real money on the resale. And run the dues through your yield math, $180 a month is $2,160 a year off your cash flow before you've paid for anything else.

What's the count actually at right now? If they're under the cap with room, this is a paperwork problem. If they're at it or over, I'd want to know what the board has done about it before I put money in.