Protection Pillar · 2026

TDSR stress test Singapore: why your bank's calculator gives you false comfort

By Winfred Quek · 10-minute read · Last reviewed May 2026

Quick answer: Singapore's Total Debt Servicing Ratio (TDSR) caps total monthly debt obligations at 55% of gross monthly income. Banks apply a stress test rate of 4% p.a. (or the actual rate, whichever is higher) when computing mortgage quantum. Variable income (commissions, bonuses, rental) is typically haircut by 30% in the TDSR calculation. The result: most borrowers qualify for 10–20% less than their online mortgage calculator suggests.

Facts verified: May 2026 · Sources linked below

Key Takeaways

• The MAS TDSR framework caps total monthly debt at 55% of gross monthly income this is a regulatory floor, not a bank policy, so every licensed lender in Singapore applies it identically.
• Banks stress-test your mortgage at 4% p.a. (or the actual rate if higher) a borrower who qualifies comfortably at 2.5% floating may find their borrowing capacity cut by 15–20% under the stress test.
• Variable income (commissions, bonuses, rental) is haircut by 30% in TDSR calculations a borrower earning $8,000 fixed and $4,000 variable has only $10,800 of income recognised, not $12,000.
• HDB flat buyers face an additional MSR (Mortgage Servicing Ratio) cap of 30% of gross income on the HDB loan this is stricter than TDSR and limits HDB loan quantum more severely for high earners.

Almost every client I meet has used an online mortgage calculator. Almost none of them understand that the number it produces is softer than what will happen when they submit a real application. The gap between "what the calculator says I can borrow" and "what the bank actually approves" is routinely 10–25%. That gap is where stressed buyers get surprised at IPA stage.

This article explains how the MAS Total Debt Servicing Ratio (TDSR) framework actually works, including the 4% stress test rate, variable income treatment, and the assumptions bank calculators quietly make that inflate your theoretical borrowing power.

What Is Singapore's TDSR and How Does It Cap Your Borrowing?

According to MAS Notice 645, the Total Debt Servicing Ratio is a regulatory requirement that caps your monthly debt obligations (including the new mortgage) at 55% of your gross monthly income. It's not a bank policy every licensed lender in Singapore applies it identically.

Debt obligations counted under TDSR include: all outstanding mortgages, car loans, credit card minimum payments, personal loans, student loans, and any guaranteed debts. Not counted: household expenses, insurance premiums, school fees.

2. The 4% stress test rate, the core mechanic

When banks calculate your TDSR for a new mortgage, they don't use the actual rate you'll pay (say 3.2% fixed). They use a stress test rate, currently 4% for residential property, to compute the hypothetical monthly mortgage.

This means the bank runs two calculations:

Approval calculation: Your monthly payment at 4% over the tenure. This is what must fit within 55% TDSR.
Actual payment calculation: Your monthly payment at the contracted rate (say 3.2%). This is what you actually pay.

The difference protects borrowers from rate shocks. If rates rise from 3.2% to 4%, your actual monthly payment rises, but it's still within the stress-tested approval threshold, so you shouldn't be overstretched. This is the regulatory intent.

3. Why bank calculators overstate your capacity

Public-facing mortgage calculators often:

Use the current rate (not the 4% stress rate). Your "max loan" number inflates by 10–15% versus reality.
Assume 30-year tenure even when your age caps it at 25 or 20. Max tenure = 65 (or loan maturity by age 65) minus your current age, or 30 years, whichever is shorter. Older borrowers see real caps.
Use gross income without variable income haircuts. Bonus, commission, rental income are discounted by 30–50% in real applications.
Assume no other debt. The user may have forgotten a car loan or credit card facility, which reduces approvable amount.

The net effect: a calculator that says "S$2M approvable" may translate to S$1.6M at the real application desk. That's the gap that blindsides buyers at IPA.

How Is Variable Income Treated in the TDSR Calculation?

MAS requires banks to discount variable income by a specified haircut before including it in TDSR computations. The rule of thumb:

Income type	Treatment
Basic monthly salary	100% counted
Performance bonus (annual)	70% counted, averaged over 2 years
Sales commission	70% counted, averaged over 2 years
Self-employed income	70% counted, averaged over 2 years
Rental income from other properties	70% counted (less vacancy allowance)
Dividend / interest income	70% counted, averaged over 2 years

For a professional whose total income is heavily weighted to bonus or commission, this haircut can cut approvable loan by 15–20%. A S$25k/month banker with S$10k base and S$15k avg variable has a TDSR income of S$10k + (S$15k × 0.7) = S$20,500/month, not S$25k.

5. The Loan Tenure Limit, the age variable

Maximum loan tenure for residential property:

HDB flats: 25 years (if using HDB loan) or 30 years (if using bank loan)
Private residential: 30 years, OR loan maturity by age 65, whichever is shorter

A 45-year-old applying for a private condo loan has max tenure of 20 years (matures at 65). A 30-year-old has full 30-year tenure. The shorter tenure for older borrowers means higher monthly instalments, which tightens TDSR headroom.

This is why upgrading late (in your 50s) with a new 20-year tenure on a larger asset is materially harder than upgrading at 40. The stress test cuts deeper.

6. What TDSR actually protects against

The 4% stress rate protects against rate shock, if SORA rises meaningfully, you shouldn't be pushed into default. Historical data suggests 4% is a reasonable buffer over the long-run SORA average of ~2–3%.

What TDSR does not protect against:

Income shock, job loss, business slowdown, variable income evaporation. TDSR assumes income continues.
Life-event cost shock, medical emergencies, family obligations, education costs. TDSR doesn't see these.
Multi-dimensional stress, rate rise + income drop + unexpected expenses happening together. TDSR stress-tests rate only.

The regulation protects the system (mortgage defaults) more than it protects the individual borrower from all realistic stress scenarios. Which is why my real advice is always: pass TDSR with headroom, don't target maximum approval.

7. MSR, the HDB overlay

For HDB properties (both HDB concessionary loans and bank loans on HDB), the Mortgage Servicing Ratio (MSR) applies on top of TDSR. According to MAS Notice 645, the MSR caps mortgage payments at 30% of gross monthly income a stricter floor than TDSR's 55% that applies only to HDB and Executive Condominium purchases.

For executive condo (EC) buyers, MSR applies for the first 10 years after purchase. After Year 10, the EC becomes treated as private and only TDSR applies.

8. The worked example, how the gap materialises

Couple, both 38. Combined gross income S$18,000/month (S$12k base + S$6k avg bonus). No other debt. Looking at S$2M condo, 25% down, S$1.5M loan, 27-year tenure.

Public calculator says: At 3.2% over 27 years on S$18k income, TDSR is 38%. Loan is approvable at S$1.8M+. Budget fits comfortably.

Real bank computation: Income stress = S$12k + (S$6k × 0.7) = S$16,200. Monthly payment at 4% over 27 years on S$1.5M = ~S$8,100. TDSR = S$8,100 / S$16,200 = 50%. Still under 55%, but much tighter than the calculator implied.

What happens if they aim for S$1.8M loan: Monthly at 4% stress = S$9,720. TDSR = 60%. Rejected. They'd need to either reduce loan amount, extend tenure (not possible, already near cap), or add a co-borrower.

The couple walked into the bank thinking S$1.8M was in reach. It wasn't. The calculator was sugarcoating.

9. What to do before walking into the bank

Get a proper affordability estimate. Use the affordability calculator with the 4% stress rate and variable income haircuts correctly applied.
Pull your credit report from Credit Bureau Singapore. S$6.90. Identifies debts the bank will see that you may have forgotten.
Gather 2 years of income documentation. IR8A, bank statements, commission slips. The bank will ask.
Pre-compute TDSR manually. (Monthly mortgage at 4% + existing debt obligations) ÷ haircut-adjusted monthly income. Should be under 55%.
Leave headroom. Don't target 54% TDSR. Target 45–50% so you're not one income fluctuation from stress.

10. How TDSR fits the Protection pillar

In the Property Portfolio Analysis, the TDSR stress test and affordability buffer sit in the Protection pillar, what protects your financial position under adverse scenarios. I run every client's affordability at three stress levels:

Policy stress: Current rate + regulatory 4% stress = the IPA number.
My stress: Current rate + 5% (one percentage point above MAS stress) to test the next cycle up.
Shock stress: Current rate + income loss scenario, what if primary earner loses job for 6 months?

If the plan survives all three, we proceed. If it survives only the first two, we revisit the loan size, tenure, or target property. If it barely survives the first, we pause. Affordability is not just about getting approved, it's about staying solvent when life happens.

The bank's stress test is a floor. Your own stress test should be the ceiling you actually plan to.

Book the Property Portfolio Analysis

Two hours. We run your affordability honestly, 4% stress, variable income haircuts, multi-scenario stress testing. You know exactly what you can take on with clean headroom, before the bank's application pipeline.

WhatsApp to book Contact form Affordability calculator

Winfred's Take

The stress test at 4% catches people who qualified comfortably at 2.5% floating rates in 2021. If your household income dropped, you took on a car loan, or your spouse stopped working since you last checked your TDSR, re-run the numbers before assuming the bank will say yes. I've had clients at IPA stage discover they're $200,000 short of their target budget because a $1,500/month car hire-purchase they forgot to mention collapsed the last 10% of their qualifying capacity. TDSR has no exceptions for good intentions.