A bank may advertise a mortgage with a low starting interest rate while the Letter of Offer shows several different spreads for later years. How can both be true? A floating-rate mortgage commonly combines a reference rate, such as Compounded SORA, with a contractual bank margin called the spread. During a promotional period that margin may be lower, then step up when the promotion ends. In this eduKateSG Quick Notes lesson, you will learn how to add the benchmark and spread correctly, compare three fictional years and understand why a good first-year rate does not automatically mean a good long-term home loan.
- Learn the equation: the all-in mortgage rate commonly equals the applicable reference rate plus its contractual spread.
- Understand the spread: it is a margin stated in percentage points, not a percentage of the benchmark.
- Check every year: promotional spreads can differ between year one, year two and later periods.
- Separate causes: the all-in rate can change because the reference rate moves or the margin changes.
- Compare payments fairly: use the current principal and correct remaining tenure for a real mortgage.
- Read the offer: identify the reference series, margin schedule, reset dates, floors and lock-ins.
Teaching paragraph 1 — learn the simple addition. Suppose a fictional floating-rate mortgage is priced at 3-month Compounded SORA + 0.55 percentage point in year one. Imagine the appropriate SORA benchmark is 1.40%. The all-in annual rate is 1.40% + 0.55% = 1.95%. The difference between 1.40 and 1.95 is 0.55 percentage point. You do not calculate 0.55% of the benchmark; the bank margin is added in rate terms. The MoneySense SORA guide explains the benchmark, while the accepted mortgage contract sets out the bank spread.
Teaching paragraph 2 — follow an illustrative margin step-up. Assume the benchmark remains at an invented 1.40% for three years solely so we can compare the spreads. The mortgage’s fictional contract says year one +0.55, year two +0.85 and year three onward +1.10 percentage points. Those produce all-in rates of 1.95%, 2.25% and 2.50% respectively. Notice that the rate has increased even though the benchmark has not moved. The reason is the scheduled promotional spread change. This matters because a borrower reading only the initial advertised rate could underestimate what the loan charges later.
Teaching paragraph 3 — separate the contract’s margin schedule from unpredictable markets. In real life, Compounded SORA may rise or fall while the bank margin is also progressing through its agreed schedule. If the reference rate falls enough, the all-in rate could still decrease despite a spread increase; if SORA rises at the same time, the two changes can add together. Singapore’s ABS home-loan guide explains that reference rates and spreads can have different conditions and notice rules. The correct learning habit is to write both components and their dates on every line, then calculate the final rate. Do not assume every change means the bank unexpectedly changed its contract.
The Four Rows of a Floating Mortgage Offer
The word promotional should prompt a specific question: what comes after the promotional period? If a loan advertises a lower year-one rate, find the year-two and later formulas before comparing the offer with another mortgage. An initially lower spread can be valuable, but its benefit may be temporary.
Some loans use a bank-administered reference instead of a publicly published benchmark. That changes how you can verify the starting number and how future changes are communicated. Read the offer’s reference-rate description, not just the headline margin.
- Reference: the specified 1-month, 3-month or other Compounded SORA series, or a different allowed reference rate.
- Spread: a percentage-point premium or discount added to or subtracted from the reference under the contract.
- Schedule: the dates or periods when a different spread becomes applicable.
- Final rate: the all-in rate after applying the correct reference, spread and any contractual floor or cap.
Worked Example: An Unchanged Benchmark with Changing Spreads
Use an invented 1.40% 3-month Compounded SORA and three contractual spreads. Year one: 1.40 + 0.55 = 1.95%. Year two: 1.40 + 0.85 = 2.25%. Year three: 1.40 + 1.10 = 2.50%.
To see the interest implication, hold a hypothetical S$400,000 mortgage principal unchanged for a simple one-month sensitivity calculation. At 1.95%, the monthly interest proxy is S$650; at 2.25%, S$750; and at 2.50%, approximately S$833.33. These numbers are not complete mortgage instalments and do not imply that the balance really stays constant for three years.
The example teaches a separation: the promotional spread changes the all-in rate under an agreed schedule, whereas loan amortisation and market-rate changes are additional factors. Never label the S$83.33 increase from year two’s proxy to year three’s proxy as the exact amount the bank will charge in that future month.
Worked Example: When the Benchmark Falls
Keep the same fictional margin schedule but let the benchmark change. If the year-one SORA is 1.40% and spread +0.55, the all-in rate is 1.95%. Suppose year two’s relevant SORA becomes 0.90% with spread +0.85: the year-two all-in rate is 1.75%. Despite a higher margin, the final rate is lower because the reference dropped by 0.50 percentage point.
This is why a borrower should not claim that every scheduled spread step-up guarantees a higher interest bill. Both moving parts must be read together. Conversely, a rising reference rate and rising spread can combine to increase costs. A contractually specified floor can also limit how far the rate declines.
Understand the rate’s components, then ask the bank for an updated instalment schedule using the actual outstanding principal, remaining tenure and reset convention.
Why Banks Add a Spread
Reference rates such as Compounded SORA reflect market funding conditions as defined by their calculation methodology. The bank’s spread is the contractual margin associated with the loan package; it can reflect the lender’s operating costs, credit risks and commercial pricing. The spread is not automatically a separate cash fee deducted from your bank account each month. It is part of the rate used to calculate interest.
The Association of Banks in Singapore’s SORA information explains the benchmark’s transactional foundation and how it is published. Different mortgage packages can use different margins, even when they reference the same Compounded SORA series. Therefore, compare the all-in contractual rate, not only the name of the benchmark.
What Happens at the Promotional Expiry?
Mark the margin change on a calendar before it occurs. A two-year low spread is not a promise about the entire mortgage’s remaining twenty or thirty years. If you are considering switching, request both the existing lender’s repricing terms and other lenders’ formal offers rather than comparing online headline rates.
The MoneySense home-loan guide specifically recommends comparing repayment schedules and the full interest-cost implications of different packages.
- The spread may increase to the next margin printed in the accepted Letter of Offer.
- The rate can also change because the benchmark has moved between fixings.
- The mortgage instalment can be recalculated using outstanding principal and remaining tenure.
- A fixed promotional rate can instead end and give way to a floating formula.
- The borrower may be eligible to review repricing or refinancing offers, subject to fees and contract terms.
- The lock-in and subsidy-clawback periods may have expiry dates different from the promotional spread period.
A Reference-Rate Reset Is Not Necessarily a Contract Variation
The reference-rate benchmark may change according to the dates already agreed in the mortgage contract. A spread may also move from one year to the next in accordance with the schedule the customer previously accepted. Such changes are different from a bank seeking to change a component beyond the original terms.
The ABS consumer housing-loan guide explains the difference between predetermined external benchmark fixings, agreed year-to-year interest changes and other interest-component changes that may require advance written notice. If the applied rate surprises you, compare the bank’s fixing date, chosen benchmark series and contractual spread against its statement before drawing a conclusion.
Never approve a suspicious digital banking prompt or provide credentials because an unsolicited message claims your spread has increased. Use the bank’s verified home-loan servicing channel.
Comparing Two Mortgage Offers with Different Promotions
Imagine Offer A has lower interest in year one but a larger margin from year three, while Offer B starts slightly higher but has a smaller later margin. There is no general answer based on first-year percentages alone. The time you expect to own the home, expected debt balance, contractual lock-in, refinance costs and the future reference rate all influence the comparison.
Ask the banks for property loan fact sheets and repayment schedules based on the same principal and desired tenure. Compare the amount of interest projected during the period relevant to you, and check the balance remaining at the end of that comparison. If one offer lowers monthly instalments only because it extends the tenure, it is not a fair simple rate comparison.
A sensible mortgage decision includes household cash-flow resilience. Even with a favourable margin, an increase in the benchmark can strain repayments if the borrower has used nearly all available income for commitments.
The Seven-Question Spread Checklist
Save the answers on one page next to the loan’s written package schedule. A borrower who understands the whole timeline can compare offers more reliably than one who memorises an attractive rate from a short video or advertisement.
- Which exact rate series is used: 1-month Compounded SORA, 3-month Compounded SORA or something else?
- Is the margin quoted in percentage points, and does the calculation add or subtract it?
- Does the margin change after one, two or three years?
- What are the effective dates of every margin change?
- Does the contract include a benchmark floor or an all-in rate floor or cap?
- When will the bank recalculate the monthly instalment?
- Are there repricing, redemption or clawback restrictions if the new rate becomes unattractive?
Ten-Minute Mortgage Spread Practice
- Minutes 1–2: define reference rate, spread and all-in mortgage rate.
- Minutes 3–4: calculate 1.40% + 0.55 percentage point.
- Minutes 5–6: repeat with spreads of 0.85 and 1.10 percentage points.
- Minutes 7–8: keep the margin higher but reduce the benchmark from 1.40% to 0.90%.
- Minute 9: explain why a reference reset differs from an unexpected change to contract terms.
- Minute 10: find the next spread-change date in a fictional mortgage offer.
Check Your Understanding
Question 1: Fictional Compounded SORA is 1.25% and the spread is 0.75 percentage point. What is the all-in rate? Answer: 2.00% before any floors or caps.
Question 2: Does a +0.80-percentage-point spread mean multiply the benchmark by 0.008? Answer: No. Add 0.80 percentage point.
Question 3: Can the all-in rate fall if the spread rises but SORA drops more? Answer: Yes.
Question 4: Must the first-year spread apply throughout the entire mortgage? Answer: No.
Question 5: Is a rate step-up already written in the accepted offer necessarily a surprise unilateral change? Answer: No. It may be a pre-agreed change.
Common Mistakes to Correct
- Reading only the initial promotional rate.
- Multiplying the spread by SORA instead of adding percentage points.
- Using today’s daily SORA when the contract specifies 3-month Compounded SORA.
- Assuming every higher mortgage rate is caused solely by the benchmark.
- Failing to recognise later-year contractual margin step-ups.
- Treating a simple interest proxy as the full actual mortgage instalment.
- Comparing different lenders’ packages without matching principal, tenure and fees.
Continue with Banking Quick Notes
Read Mortgage Rate Resets · Fixed and Floating Home Loan Rates · Mortgage Rate Floors and Caps · Mortgage Promotional Spreads · Mortgage Cashback and Clawbacks · Mortgage Redemption Notice Periods. More lessons are in Quick Notes.
Original Sources and Final Rule
Official sources: MoneySense: Switching to SORA, MoneySense: How Home Loans Work, ABS: Key Housing Loan Questions and ABS: About SORA. Every numeric benchmark and spread here is invented solely for learning. Final rule: read the benchmark and the margin for every period, add them correctly, then check the loan’s actual repayment terms.