Many fail to realize vendors will carry commercial general liability coverage and workers compensation (if they have employees), but many do not carry professional liability/E&O coverage.

Depending on your definition of house hack, these excess losses may be able to be carried forward as passive losses on form 8582 (not enough information to determine this part, would need additional info).I will mention as well that if you choose to switch to another accountant who more specializes in real estate, being that it's April, any good CPA will automatically want you to file an extension.

We haven't discussed terms of his owner carry yet (10% down).

I believe you can carry those loses forward to next year though. 

I think the confusion is between active business losses which can be deducted verses passive investment losses, which I believe must be carried forward, beyond a certain limit anyway.

Commercial financing carries more risk, and higher closing costs, but can be great if done right, on the right property, in the right location.

And most DSCR Lenders still are limited at a maximum of four units and don’t carry this option.11+ Units: For investors that are looking at multifamily investment properties with 11 units or more – then the loan options are going to look very different than the two other buckets (2-4 units or 5-10).

It's a gamble doing this, but a great way to start... but imagine your renter bailing on you after a few months - can you afford to carry the place for a month or two?

You can register your STR's at the link @Carrie Foley provided and the current response time is ~2 weeks based on my submissions.

If you are making more than $150,000, your rental loss, if considered passive, will be suspended and carried forward unless you can claim real estate professional status.