Quote from @Immanuel Sibero:
Hi @Immanuel Sibero and @David M. , I'm excited for more math brains to discuss this with! Let's understand this very simple example first:
Suppose it's an interest only loan. Define the variables: interest rate i, annual debt service DS, loan amount LA, purchase price PP, net operating income NOI, cash on cash COC, and cap rate C.
Since it's an interest only loan,
i x LA = DS (interest rate times loan amount equals annual debt service).
Now suppose the interest rate equals the cap rate: i = C.
Then I claim the COC = i = C. In other words, the COC is equal to both the interest rate and cap rate.
Here's the proof:
Since i = C, DS/LA = NOI/PP.
That's the same as saying NOI/DS = PP/LA. Call this ratio r.
So r = NOI/DS = PP/LA.
Then NOI - DS = r*DS - DS = (r-1) * DS
and PP - LA = r*LA - LA = (r-1)*LA.
So COC = (NOI - DS)/(PP-LA) (by definition)
which is = (r-1)*DS/(r-1)*LA = DS/LA = i = C.
I'm trying to understand this in WORDS though. If the rate of payment (interest rate i) equals the rate of return (cap rate C), then WHY is the return on investment (COC) also equal to these rates? I can understand it mathematically, but not in practice.
@Immanuel Siberoundefined