I'm trying to learn more about capital gains tax when selling a rehabbed home or refinancing for the equity.

Consider the cost of the property, mortgage payments, property taxes, insurance, maintenance, and property management fees (if applicable).

Worst case the irs says he should have charged interest and he owes $20-30 in taxes. 

Seller financing still implies a transaction and therefore a tax event.

CPAs that really know the back and front of not only fix and flip but investing write offs/tax liability. 

Every day I wake up to look at Google News and there is at least one article about Foreclosure, or Fixed Income Tenant can't stay where they have been from before the Covid or the Widow who has lived in the 2/1 house for 50 years cannot pay the increases in Property Tax, Home Owner's Insurance, Lights, Water and everything else.

@Michael Shea I'm not a tax accountant, but I've done the rent by room strategy for over 6 years as a house hacker, and I've recognized rent by room tenants rents in the Schedule E part of the tax return.

I pulled them from the tax assessor's website, just going one by one through each parcel to locate and identify the vacant lots.

Think of it like the escrows you likely pay your mortgage servicer for Insurance and Taxes, or your estimated taxes to IRS.  

Here are a few tips to help you get started:Attend Houston-area seminars, networking events, and meetings for real estate.