Fixed, ARM, Points, and Buydowns: Choosing a Mortgage Without Guessing
Almost every mortgage choice comes down to a question you can answer — how long will I hold this loan — and one you cannot: where will rates go. Structure your decision around the first, and treat any product that only works if the second goes your way as a bet rather than a plan.
The choice matters because the mortgage, not the price, determines your monthly cost. Two buyers paying the same price for the same house can have materially different payments, and the difference compounds over decades.
Fixed-rate or adjustable?
A fixed-rate mortgage holds the same rate for the full term, typically 30 or 15 years. Your principal and interest payment never changes. It is the default for good reason: it removes an entire category of risk from your life, and it lets you plan.
An adjustable-rate mortgage (ARM) carries a fixed rate for an initial period — commonly 5, 7, or 10 years — and then adjusts periodically against an index. The initial rate is usually lower than the comparable fixed rate. That discount is the lender paying you to accept the risk of what happens after the fixed period ends.
An ARM is a reasonable choice when you have a concrete, high-confidence reason to believe you will sell or refinance before the adjustment: a fixed-term job assignment, a stated plan to move when a child finishes school, a property you are explicitly buying as a stepping stone. It is not a reasonable choice because you vaguely expect to move eventually, or because rates seem likely to fall.
If you do consider one, read the caps: the initial adjustment cap, the periodic cap, and the lifetime cap. Then calculate the payment at the lifetime maximum and ask whether you could pay it. If the answer is no, the product is not suitable at any starting rate.
Thirty years or fifteen?
A 15-year loan carries a lower rate and dramatically less total interest, at a substantially higher monthly payment. A 30-year loan costs more overall and leaves you more monthly flexibility.
The under-discussed middle path: take the 30-year and make additional principal payments voluntarily. You capture much of the interest saving while retaining the ability to stop in a bad month. A 15-year commitment is a commitment; the extra payment on a 30-year is not.
The counterargument is behavioral and honest — most people who intend to pay extra do not. If you know that about yourself, the 15-year enforces the discipline.
Are points worth buying?
Points are prepaid interest: you pay cash at closing to lower your rate for the life of the loan. Whether they pay off is arithmetic, not opinion.
Divide the cost of the points by the monthly payment saving. That gives you the break-even in months. If you hold the loan past break-even, you win; if you sell or refinance before it, you lost the money.
The comparison people forget is what else that cash could do — a larger down payment, reserves, or paying off higher-interest debt. Points are worth it for buyers confident they are staying put for a long time, and a poor use of cash for buyers who are not.
What about a temporary buydown?
A 2-1 buydown reduces the rate by two percentage points in the first year and one in the second, returning to the note rate in year three. It is typically funded by a seller credit rather than by the buyer, which is why it appears in slower markets as a seller concession.
The critical point: you must qualify at the full note rate, not the reduced one. The temporary payment is genuinely lower, which helps in the early years — but the loan is the loan. If you are counting on refinancing before the rate steps up, you are again relying on a door you cannot guarantee will be open. Treat a buydown as a cushion, not as a way to afford a house you otherwise cannot.
How should you shop?
Get Loan Estimates from at least three lenders, on the same day, for the same loan amount and product. The form is federally standardized specifically so the comparison is honest, and the differences between lenders on fees are frequently larger than the differences on rate.
Multiple mortgage inquiries within a short shopping window are treated as a single inquiry by the major credit-scoring models, so shopping does not meaningfully damage your credit.
Consider more than one type of lender — a large bank, a local credit union, an independent mortgage broker. In Greater Boston, local credit unions are frequently competitive and are sometimes more flexible on condominium project review.
And weigh responsiveness alongside rate. In a competitive market, a loan officer who answers a listing agent's call on a weekend materially strengthens your offer. See our guides to pre-approval and winning a bidding war.