Howdy @Amadeus Hladun
The most important number you need to establish is the ARV. Everything else is derived or subtracted from that number. Let me show you what I mean using your numbers.
ARV x LTV = Refi Amount - Rehab Cost - Closing Costs - Holding Costs = MAO
ARV $450,000
x 70% - 80% (LTV) = this is your All-in Costs target = x 80% = $360,000 (Refinance Loan Amount)
- Rehab Cost $50,000
- Closing Costs $ ???? (Acquisition Loan, HML Points, Refinance Fees)
- Holding Costs $ ???? (This includes mortgage payments, taxes, insurance, utilities, HOA fees, etc. that occur during the Rehab Phase and up until the property is fully rented)
= $310,000 (not including Closing and Holding Costs) Maximum Allowable Offer
Your Purchase price of $250,000 is below this amount. That is good considering you did not provide Closing and Holding Costs. The Cash-out Refinance loan will cover the $250,000 Purchase price and $50,000 Rehab. That leaves $10,000 cash remaining to cover the Closing and Holding Costs. If they add up to more than $10,000 that overage will remain in the property as equity.
You now have $90,000 remaining in property as equity. ($450,000 - $360,000)
Yes you put $360,000 as the Refinance amount.