Lower Rates Don't Increase How Much You Can Borrow

Singapore mortgage rates have roughly halved in a year. A loan that cost 3% in 2024 can be had near 1.3% today. The natural conclusion — the one buyers reach at viewings and agents quietly encourage — is that a cheaper rate means a bigger budget: if each dollar of loan now costs less to service, surely the bank will lend more of them. It won't. Your maximum loan barely moves with the actual rate, because banks aren't allowed to size your loan at the rate you pay. They must size it at a stress-test floor that has sat at 4% for residential property throughout the whole cheap-rate era (MAS). The low rate shrinks what you pay. It does almost nothing to what you can borrow.

Two different rates do two different jobs

Every home loan in Singapore is governed by two numbers that are easy to confuse.

The first is the actual rate — the 1.3% (or 1.40% fixed) you're quoted. It determines your real monthly repayment and your total interest. When rates fall, this number falls, and your bill genuinely drops.

The second is the sizing rate — the rate the bank plugs into the affordability test that decides your maximum loan. For residential property, MAS requires that test to use the higher of your actual rate or a 4% medium-term interest rate floor (MAS). Since 1.3% is well below 4%, the floor always wins. The bank computes your borrowing limit as if your loan cost 4% — even though you'll pay a third of that.

So a falling actual rate makes your existing loan cheaper, but it can't lift your borrowing limit, because the limit was never calculated off the actual rate in the first place. Until the actual rate climbs above 4%, your maximum loan is frozen to the floor.

The worked gap

Take a household earning $12,000 a month with no other debt. The Total Debt Servicing Ratio (TDSR) caps total loan repayments at 55% of gross income — here, $6,600 a month (MAS). The question is how big a loan that $6,600 supports, and the answer depends entirely on which rate you size it at, over a 30-year tenure:

At their real 1.3% rate, $6,600 a month looks like it should support a $1.97 million loan. The bank, sizing at the 4% floor, will approve about $1.38 million. The difference — $584,000, or 42% — is borrowing power that feels available but isn't. It's the single most common miscalculation we see buyers make in a low-rate market: budgeting off the rate they'll pay, not the rate they're tested at.

Why the floor exists (and why you should be glad it does)

This isn't bureaucratic friction; it's the entire point of the rule. Today's 1.3% is near a multi-year low. A 30-year loan will live through several rate cycles, and at some point the actual rate will likely sit nearer the floor — or above it — than it does now. Sizing your loan at 4% is MAS forcing the question "can this household still afford the loan when rates normalise?" before the loan is written, rather than after.

You can see the cushion in the same example. On the $1.38 million loan the bank actually grants, the repayment at the real 1.3% rate is only about $4,640 a month — just 39% of the $12,000 income, well under the 55% cap. That roughly $1,960 of unused monthly headroom isn't the bank being stingy. It's the buffer that absorbs a rate rise: if this loan repriced to 4% down the line, the payment would climb toward the $6,600 the household was tested against — and they'd still cope. The borrower who games their way to the full 1.3%-implied $1.97 million has spent that buffer in advance, and is the one who gets squeezed when the cycle turns.

What this changes for buyers

Don't shop off your repayment — shop off your approved quantum. A cheap rate makes a given property more comfortable to hold; it does not make a more expensive property attainable. If your loan is capped at $1.38 million, that cap holds whether the rate is 1.3% or 3%. Get the loan sized — an in-principle approval — before you fall in love with something priced off the rate you pay rather than the rate you're tested at.

Levers that actually move your quantum are income, tenure, age and existing debts — not the headline rate. Extending tenure (subject to the 30-year private / 25-year HDB caps and age limits) lowers the monthly figure the floor produces and lifts the loan. Clearing a car loan frees TDSR room. A second income added to the application raises the 55% base. These shift the limit; a rate cut essentially doesn't.

For HDB and EC buyers, a second cap bites first. On top of TDSR, the Mortgage Servicing Ratio (MSR) limits the housing loan alone to 30% of gross income, and it's also stress-tested at 4%. For many HDB buyers the MSR — not the actual rate — is the true ceiling, and a cheaper rate does nothing to lift it.

The bottom line

It's worth holding the two ideas at once: 2026's low rates are a real gift to anyone servicing a loan, and almost irrelevant to anyone trying to enlarge one. The bank stress-tests you at 4% precisely so that a temporary cheap rate doesn't tempt households into loans they can't carry through the cycle. Budget off the $1.38 million the floor allows, enjoy the fact that at 1.3% it only costs you $4,640 a month to hold — and treat the extra $584,000 the cheap rate seems to offer as exactly what it is: an illusion the rule is there to stop you from buying.

General information only, not financial advice. TDSR threshold (55%), the residential medium-term interest rate floor (4.0%) used to compute maximum loan size, and the MSR cap (30%, HDB/EC) are MAS requirements current as at June 2026 and may change (MAS — calculating TDSR, MAS — MSR & TDSR rules). Maximum-loan figures were computed for the stated assumptions ($12,000 gross monthly income, no other debt, 30-year tenure, 55% TDSR) and exclude individual factors like age, variable-income haircuts and existing commitments that banks also apply. Verify your own eligibility with a bank.

Silas Tan is a District Director at Huttons Asia and co-founder of TRIBE. CEA Registration R000303I. Methodology published. No spin.