How does an interest offset mortgage work in Singapore?

An interest offset mortgage links a savings account to your home loan. Every dollar in the linked account offsets the same amount of outstanding mortgage principal for interest calculation. If you have $200,000 in the account and $800,000 outstanding, you pay interest only on $600,000. DBS and UOB both offer IOM structures in Singapore.

Is an interest offset mortgage worth it in Singapore?

An IOM justifies itself when you hold at least 20% of your loan balance in liquid cash in the linked account. The rate premium over standard fixed (0.1–0.2%) is outweighed by the effective 1.5–1.7% return on parked cash -- far better than regular savings accounts paying 0.05–0.1%.

Last reviewed: 19 May 2026

Interest Offset Mortgage Singapore 2026: How It Works and When the Maths Justifies It

By Winfred Quek · CEA R073319H · Crestbrick

Quick answer: An interest offset mortgage (IOM) links a savings account to your home loan every dollar parked in the linked account reduces the principal on which interest is charged. With DBS or UOB IOMs in 2026, mortgage rates on the offset portion are ~1.5–1.6%, making the "return" on parked cash far better than a regular savings account at 0.05–0.1%. The IOM justifies its ~0.1–0.2% rate premium once you consistently hold at least 20% of your loan balance in the linked account.

Facts verified: May 2026 · Sources linked below

How an Interest Offset Mortgage Actually Works

A standard mortgage charges interest on the full outstanding principal every day. An interest offset mortgage (IOM) instead charges interest on a reduced principal: the outstanding loan minus the balance in a designated linked savings account.

Example: $800,000 loan outstanding. $200,000 in the linked account. Interest charged on $600,000 only. The $200,000 earns no conventional interest in the savings account instead, it "earns" at your mortgage rate (1.5–1.6%) by reducing the interest you pay.

Critically, your monthly repayment schedule does not change. The full scheduled payment goes through as normal. But because interest accrues on a smaller principal, a larger portion of each payment reduces principal meaning you pay off the loan faster for the same monthly outlay.

Which Banks Offer IOM in Singapore?

Bank	Product Name	Offset Rate (2026)	Premium Over Standard Fixed	Available For
DBS	DBS Multiplier Mortgage	~1.60–1.70%	+0.10–0.15%	Private residential
UOB	UOB One Home Loan	~1.55–1.65%	+0.10–0.15%	Private residential
OCBC	OCBC Frank Mortgage (limited)	Varies	+0.10–0.20%	Private residential

IOM products are not available for HDB loans. Check with each bank for current availability and exact rates product offerings change.

The Interest Savings: Real Numbers on a $1M Loan

The table below shows annual and total interest saved over 25 years, depending on how much you park in the offset account. Assumes a 1.6% IOM rate, $1,000,000 outstanding loan, and the stated offset balance maintained consistently throughout.

Offset Balance	Effective Principal Charged	Annual Interest Saving vs No Offset	Total Saving over 10 Years	Total Saving over 25 Years
$0 (no offset)	$1,000,000
$100,000 (10%)	$900,000	~$1,600/yr	~$16,000	~$40,000
$200,000 (20%)	$800,000	~$3,200/yr	~$32,000	~$80,000
$300,000 (30%)	$700,000	~$4,800/yr	~$48,000	~$120,000
$400,000 (40%)	$600,000	~$6,400/yr	~$64,000	~$160,000

Simplified illustration assuming flat offset balance. In practice, the loan principal reduces over time, so actual savings taper. Rate premium cost (~0.15% on $1M = $1,500/yr) should be netted off these savings.

The Break-Even Calculation

An IOM charges a rate premium of approximately 0.10–0.20% over a standard fixed rate. On a $1M loan, that premium costs $1,000–$2,000/year in additional interest.

The IOM saves 1.6% per year on the offset balance. Break-even: you need an offset balance where 1.6% × balance > premium cost.

Premium of $1,500/yr ÷ 1.6% = offset balance needed: ~$93,750
So if you can consistently park $94,000+ in the linked account, the IOM saves money vs standard fixed
At $200,000 offset, net annual saving ≈ $3,200 − $1,500 = $1,700
At $300,000 offset, net annual saving ≈ $4,800 − $1,500 = $3,300

Opportunity Cost Comparison: Where Else Could That Cash Go?

Cash Deployment Option	Effective Annual Return	Risk	Liquidity
IOM offset account	1.60% (mortgage rate)	None	Full withdraw anytime
Regular savings account	0.05–0.10%	None	Full
T-bills / SSB (6-month)	~2.5–3.0%	Very low	Medium (6–10yr for SSB)
Fixed deposit (12-month)	~2.5–3.0%	None	Low (locked for term)
CPF OA (if top-up eligible)	2.5% guaranteed	None	Very low (locked until 55)

The IOM offset "return" of 1.6% beats a savings account substantially but loses to T-bills and fixed deposits on raw yield. The IOM wins on full liquidity you can withdraw the offset balance at any time without penalty.

Key constraint: The IOM linked account must hold cash not CPF. This limits it to buyers with substantial liquid savings. If your cash buffer is below $100,000, the standard fixed rate is almost certainly better. Also note: the offset benefit disappears if you withdraw the parked funds, so this requires genuine commitment to keeping the cash idle.

Who Should Consider an IOM?

High cash reserves, low investment conviction you have $200K+ in cash that is not going into equities or fixed deposits. The IOM gives a liquid 1.6% on that cash with zero lock-in.

Business owners with lumpy cash flow cash flows in and out of the offset account as the business needs it, and you benefit during periods when high balances reduce mortgage interest.

Approaching full repayment if you have $600K+ in the offset against an $800K loan, you are effectively paying interest on $200K. At 1.6%, that is $3,200/year in interest far cheaper than carrying the full loan.

Emergency fund integration parking your 6–12 month emergency fund (say $60K–$120K) in the offset account makes it work harder than a savings account while keeping it fully accessible.

IOM vs Partial Prepayment: Which Is Better?

Some borrowers wonder whether to make a partial prepayment (reducing the principal permanently) versus parking cash in an IOM. The answer: IOM almost always wins, because it preserves optionality. A partial prepayment cannot be reversed the cash is gone from your balance sheet. An IOM offset allows you to withdraw the parked cash if you need it, while achieving the same interest saving while the funds remain deposited.

The only exception: if your mortgage has a free partial prepayment clause allowing you to reduce principal without penalty (some DBS packages allow 10% p.a. prepayment free), and you are certain you will never need the cash, a prepayment at 1.6% effective return matches the IOM.

Want to run the numbers on your situation?

Book a Free 30-Min Session