I've seen a few hundred dollars for lease renewals versus they may charge a month's rent to find a tenant and you are reducing the risk of having a bad tenant with the turnover.

Disallowed losses under wash sale rules increase the cost basis of replacement securities, potentially reducing future taxable gains.This post does not create a CPA-Client relationship.

And all of this happens during the contract period reducing purchasing risk.Great strategy especially when practiced just on the outskirts of a major metro area in a country setting(a weekend getaway property that can be marketed to city folk).  

Freddie has similar intricacies, but also does not require a two year history of receipt; https://guide.freddiemac.com/app/guide/section/5306.4If you can use the rental income to drive the DTI down so that you can reduce the down payment similar to that of the FHA product, the benefits of the conventional option will outweigh the FHA option, as I'm assuming you have a strong FICO based on rate quoted with no points.  

Using a 401(k) loan reduces your emergency liquidity, which could make the investment riskier if unexpected costs arise.

It’s hit and miss, really need to deeply understand what they offer, if they will work for you or against you, whether they sign the lease or you (I prefer me, to reduce that lock jn). 

I have dabbled in real estate, but never heard of brrrr before now, and transparently never did much research outside of knowing that property ownership was a way to reduce my taxable income. 

Contributing to a Solo 401(k) or SEP-IRA can reduce taxable income, and Section 179 or bonus depreciation lets you deduct equipment costs upfront.

Showing ID is not only a safety measure for yourself and the other person, it also helps to reduce fraud if someone is unwilling to provide identification and is being this difficult with a simple ask, then I would also question whether or not they would be a good fit as a tenant

It’s still a worthy strategy to force cash flow that’s rare to find in SoCal, especially if you can reduce the cost of construction by doing a conversion/using an ADU grant or even buying a property with an existing ADU In general, even if the ADU valuation matches your cost including grants, they are usually not worth it in southern CA in single family zones.