Whether to Buy & Hold or Flip a Property

[George Sass]

I have a house that I can't decide whether I want to hold or flip. I bought the house for 40k and I believe that if I sold it after renovating, I can earn approx. 25k after all expenses and closing costs. However, if I hold onto it, I can get approx. 1k/month in rent. I can see the positives for both options. My overall plan is to flip houses while slowly adding rentals to my portfolio to generate some passive income. Any advice?