Your Mortgage May Not Rise When the Fed Rate Does

On 16 September 2026, the US Federal Reserve’s policy-setting committee unanimously raised its federal-funds target range by 0.25 percentage point, to 3.75%–4.00%.[S1] For a Singapore homeowner, however, the date that determines the next mortgage instalment may be sitting quietly inside the loan’s facility letter.

That is because a Fed increase does not flow instantly or equally into every Singapore home loan. Banks subsequently raised rates on selected fixed and floating packages, but existing borrowers will feel any change according to their own benchmark, interest-rate review date and contract terms—not simply because the Fed moved.[S2][S3]

Find the date that controls your loan

Start with the facility letter, which records the agreed terms between borrower and bank. Look for four items:

• whether the loan is fixed or floating;
• when a fixed or promotional rate expires;
• which benchmark and tenor apply, such as one- or three-month compounded SORA;
• how often the interest rate is reviewed or reset.

SORA—the Singapore Overnight Rate Average—is calculated from eligible overnight borrowing transactions reported by banks. The Monetary Authority of Singapore publishes the daily rate on the next Singapore business day, as well as compounded SORA figures covering one, three and six months.[S4]

A floating package is commonly expressed as compounded SORA plus the bank’s margin, or “spread”. If the applicable SORA is 2.8% and the contractual spread is 0.8 percentage point, for example, the all-in rate would be 3.6%. That is only an explanation of the formula, not a current rate quote.

The tenor matters too. A mortgage tied to three-month compounded SORA does not work in exactly the same way as one tied to one-month compounded SORA. Its rate also changes only according to the review mechanism stated in the contract. This is why two neighbours with the same bank—and even similar outstanding balances—can face different instalment changes at different times.[S3][S4]

A fixed-rate borrower may see no immediate change at all. The important date could instead be the end of the fixed period, when the loan moves onto its contractual follow-on rate or becomes eligible for another package.

What a quarter-point difference looks like

Consider a fully amortising loan balance of S$500,000, with 25 years left to run. If the all-in interest rate changed from an assumed 3.00% to 3.25%, the calculated monthly instalment would rise from about S$2,371 to S$2,436—a difference of roughly S$65 a month.[S5]

On a S$1 million balance with the same remaining term and assumed rates, the increase would be about S$131 a month.[S5] These are repayment illustrations, not predictions of SORA or quotations from a bank. An actual instalment will depend on the outstanding principal, remaining tenure, applicable rate and the bank’s calculation method.

The comparison is useful because it puts a dramatic-sounding rate announcement into household terms. A quarter-point increase may be manageable for one family but uncomfortable for another, especially when it coincides with the end of a promotional package or a change in household income.

It also shows why focusing only on the advertised opening rate can mislead. A slightly cheaper rate may produce modest monthly savings, yet switching costs or a fresh lock-in period could change the overall result.

A dual-key layout changes the household calculation

A genuine dual-key home is more than an ordinary multi-bedroom unit with a lockable bedroom. It generally comprises one property under a shared title, designed with a main living area and a distinct secondary zone, often with separate access shown on the approved floor plan.

That physical arrangement can serve different household choices. A parent or adult child might have greater privacy while remaining close to the family. Guests may have their own entrance and bathroom. In some homes, the secondary zone may be occupied by a tenant—but the layout itself does not grant permission to rent it separately, operate it as co-living accommodation or treat it as a second legal dwelling. The property’s applicable ownership and occupancy rules still have to be checked.

For mortgage planning, separate the layout’s use value from any hoped-for income. If the secondary zone lets an older parent live with the family instead of maintaining another home, that may reduce total household costs even without rent. If it gives an adult child privacy, its value may be practical rather than financial.

Where rent is being considered, avoid taking a published one-bedroom rental figure and treating it as a verified dual-key return. A secondary zone may differ from a conventional one-bedroom unit in floor area, kitchen facilities, privacy, utilities and access. Relevant evidence would include comparable rentals with genuinely similar layouts and conditions—not merely the same bedroom count.

A cautious affordability calculation should therefore test the mortgage without assuming uninterrupted rent. Any possible contribution can then be modelled separately, after allowing for vacancy, maintenance, agent fees where applicable and other ownership costs. That prevents an uncertain side income from becoming the figure holding the whole loan together.

Reprice, refinance or wait?

Once the next reset date and likely repayment are clear, there may be three broad choices. Repricing means switching to another package with the same bank. Refinancing means moving the loan to a different bank. Waiting may also be reasonable where a borrower remains inside a lock-in period or where the available savings are too small to cover switching costs.

Repricing can involve less paperwork and may avoid the legal and valuation expenses commonly associated with refinancing. But it is not necessarily free: one lender currently lists a S$1,000 administrative fee for repricing, alongside its own eligibility conditions of at least S$100,000 outstanding and five years of remaining tenure.[S6] Those are that lender’s terms, not a market-wide standard.

Compare packages over a common period rather than stopping at the first-year rate. Include the bank spread, benchmark tenor, fixed or promotional period, subsequent rate, lock-in, clawbacks and all cash fees. A package saving S$70 monthly would take more than 14 months to recover a S$1,000 fee, before considering any other costs; that arithmetic is more useful than choosing solely from a headline rate.

Banks had already adjusted selected packages after the September Fed decision, which means quotations can move while a borrower is considering the options.[S2] Request written figures and check how long each offer remains valid.

The document to read before making a move

The Fed decision supplies the news, but the facility letter supplies the household timeline. Find the benchmark, spread, reset frequency, fixed-rate expiry and lock-in end date. Then ask the bank for the instalment that would apply under the relevant contractual rate, rather than assuming an immediate 0.25-point rise.

For a dual-key household, run that number twice: first using dependable household income alone, and then with a clearly labelled estimate for any lawful, realistic contribution from the secondary zone. The first calculation shows whether the home remains affordable on its own terms. The second shows what the layout may add—without pretending that an extra door automatically creates a second home or a guaranteed yield.