A trust deed investor I have worked with for years asked me a fair question last month while we were looking at a flip loan on a house near the east valley. The borrower was gutting the place and would not see a dollar of rent or sale proceeds for months. So how, he wanted to know, was he supposed to get his monthly check when the guy paying him had no income coming off the property? The answer was three words that a lot of passive lenders have never had explained to them: an interest reserve.
Here is the short version. On a fix-and-flip or ground-up construction loan, the lender sets aside a chunk of the loan amount at closing to cover the borrower’s monthly interest for a set number of months. That reserve, not the borrower’s checkbook, is what pays you each month while the project has no income. It keeps your yield flowing on schedule, and it is one of the first things you should look for before you fund a rehab or construction deal.
Why a rehab or construction loan needs a reserve at all
A finished rental pays for itself. A construction site does not. During a flip or a build, the property produces nothing, and the borrower is usually pouring their own cash into materials, labor, and permits. Asking that same borrower to also write you an interest check every month out of pocket is how good projects stall and how loans slip into default for reasons that have nothing to do with the real estate.
The interest reserve solves that. Instead of relying on the borrower’s monthly discipline and liquidity, the lender pre-funds the interest. On a 12-month loan, the lender might hold back enough to cover nine or twelve months of interest right off the top. That money never reaches the borrower’s hands. It sits in a controlled account and gets released to you, the investor, on the same day each month.
How the money actually moves
The mechanics are simpler than they sound once you see the sequence. A reserve-funded deal generally works like this:
- At closing, the reserve is carved out of the total loan amount and held by the loan servicer or lender, not disbursed to the borrower.
- Each month, the servicer draws one interest payment from that reserve and pays it to you on schedule.
- The reserve balance ticks down by one payment every month the loan is outstanding.
- When the borrower sells or refinances, any unused reserve is credited back toward their payoff, so they only paid for the months they actually used.
The important thing is where that money comes from. The reserve is funded out of the loan proceeds, which means it is part of the total you are lending against the property. A $400,000 loan with a $30,000 interest reserve is really $370,000 of rehab and acquisition money plus $30,000 of your own capital being paid back to you slowly as interest. That is not a trick, just arithmetic you need to fold into how you judge the deal.
An interest reserve does not make a weak deal safe. It just makes sure a good deal pays you on time while the property is busy becoming worth more.
What the reserve does and does not protect
It protects your cash flow, not your principal. The reserve keeps the monthly interest flowing while the balance lasts. It does nothing about whether the finished project actually sells for enough to pay you back. Your principal is still protected the old-fashioned way, by the equity cushion between your loan and the property’s real value. A reserve is a convenience layered on top of good loan-to-value discipline, never a substitute for it.
It can also hide a struggling borrower. This is the part passive investors miss. Because the reserve pays automatically, a borrower can be badly behind on the actual construction and you would never feel it in your monthly check, right up until the reserve runs dry. That is why I care less about the fact that a reserve exists and more about how much runway it buys relative to how long the project should realistically take.
What to verify before you fund the deal
The reserve is only as good as its size and its terms. The first question is how many months it covers against how many months the project needs. A nine-month reserve on a build that honestly takes twelve is a three-month gap where the borrower has to start paying out of pocket, and that is exactly when a stretched borrower tends to stumble. I want the reserve to comfortably outlast the realistic timeline, with margin for the delays that Las Vegas permitting still throws at people.
Ask who holds the money. A reserve controlled by a neutral servicer, released on a set schedule, is far cleaner than one the lender manages loosely. Ask whether it is inside your loan-to-value number or on top of it. Since the reserve is borrowed money secured by the same property, it should be counted in the LTV, and if it is not, your real exposure is higher than the headline number suggests. And ask what happens when the reserve is exhausted. The answer should be a clear plan for the borrower to make payments directly, plus a servicer who will actually notice and tell you the moment those payments stop.
The bottom line
An interest reserve is one of the quiet mechanics that make trust deed investing on flips and construction loans work at all. It lets a borrower put their cash into finishing the project while you still get paid like clockwork, and when it is sized right it removes a whole category of avoidable defaults. Just remember what it is: a cash-flow tool funded with your own money, not a safety net for your principal. Read the term sheet for the reserve’s size, its holder, and its place in the LTV, and make sure the runway outlasts the build. Get those right and the monthly check takes care of itself.
Questions I get after this
Does the interest reserve reduce the interest rate I earn?
No, your rate is your rate. The reserve only changes where the payment comes from, not how much you earn on the money outstanding. One thing to keep in mind is that you are earning interest on the reserve portion too, since it counts as part of the loan balance, and unused reserve simply comes back to the borrower at payoff rather than costing you anything.
What happens if the borrower finishes early?
That is the good outcome. If the project sells or refinances ahead of schedule, the unused portion of the reserve is applied to the borrower’s payoff, so they stop paying interest they never used. You still collected every payment the loan was outstanding, and your capital comes back sooner to redeploy into the next deal. Early payoffs are a feature, not a loss.
Is an interest reserve the same as an impound or escrow account?
Not quite. An impound account collects money from the borrower to pay their taxes and insurance later. An interest reserve is funded from the loan itself and pays you, the lender, the monthly interest. Both are controlled accounts released on a schedule, but the purpose and the source of the money are different.
Should I avoid loans that do not have a reserve?
Not automatically. Some strong borrowers with real income choose to pay interest out of pocket to keep their loan amount and cost down, and that can be a sound deal. What I do not want is a no-income construction project relying on a borrower’s promise to pay monthly with no reserve behind it. In that case, ask hard questions about where the payments will actually come from.
Thinking about your first, or next, trust deed?
Understanding how you actually get paid is half the work of investing well in private mortgages, and the interest reserve is one of the details that separates a smooth deal from a stressful one. If you are weighing a flip or construction trust deed in Las Vegas or Henderson and want a second set of eyes on how the reserve and the numbers are structured, I am glad to walk through it with no pressure. Visit my Private Capital page or reach me through the contact page to start the conversation, and subscribe for future notes or follow along on Instagram and LinkedIn.
Beau McDougall is Executive VP of Private Capital at All Western Mortgage, NMLS #2611909. This article is educational only and is not investment or financial advice. All investments carry risk. Consult your own financial and legal advisors before funding a trust deed.
