How you financed the property purchase and the fact you did a refi is irrelevant in determining the cost basis. You cost basis of the property is the "LESSER" of
1) What you paid for it when you originally purchased it or;
2) the FMV of the property on the date it was placed in service.
While not impossible, it is very doubtful the property was worth less when you converted it from personal use to a rental, than what you paid for it when originally purchased. So you cost basis will be what you originally paid for it when you purchased it. This has nothing to do with what you borrowed from any lender. Typically, your original purchase price is listed in the sales contract you signed obligating yourself to pay the sales price to the seller, that you agreed to pay in said sales contract.
