HELOC vs Cash Out Refinance and Tax Ramifications

[Joe Wall]

I currently do not owe a house, but my parents have thought about doing a HELOC (home equity line of credit) to help me buy a side-by-side duplex. I am wondering about all the details for a HELOC. I was told it can only be 80% of the house's value. So like $300,000 would be $1800 plus 5% I'm told to repay back the mortgage. Then, I would be doing a cash-out refinance of the HELOC. What are the tax implications of this?

I guess my biggest goal is to figure out how much per month it would be for a $200,000 to $250,000 HELOC to put towards a duplex. How much would I need to pay back my parents per month?  What are the tax implications?