Co-Borrower TDSR & MSR: How Joint Income Affects Your Loan Approval

What Is Co-Borrower TDSR?

When a property loan has one primary borrower and one or more co-borrowers, MAS Notice 632 — Residential Property Loans requires that the bank count all co-borrower income toward the overall household debt servicing capacity.

Key rule (in effect since 16 December 2021):

• TDSR ceiling: 55% of combined monthly gross income
• Bank adds up all borrowers’ monthly gross income
• Total monthly debt obligations (including new mortgage) must not exceed 55% of combined income

What Is MSR?

Mortgage Service Ratio (MSR) is an additional ceiling that applies specifically to HDB bank loans and EC purchases from developer (within 10 years of TOP):

• MSR ceiling: 30% of monthly gross income
• New mortgage payment alone cannot exceed 30% of monthly gross income
• Applies to HDB resale loans, some HDB upgrade loans, and eligible EC purchases
• More restrictive than TDSR for HDB and EC borrowers

Important: MSR is stricter than TDSR for HDB and EC loans. A couple might pass TDSR (55%) but fail MSR (30%).

How Co-Borrower Income Is Counted

Banks follow strict rules on co-borrower income.

Who Can Be a Co-Borrower?

• Spouse or registered civil partner
• Adult child
• Parent or sibling
• Any person with joint liability on the loan

Whose Income Counts?

Only active co-borrowers’ income counts. If someone is listed on the loan as liable for repayment, their monthly gross income is included.

Income categories accepted:

• Salary: Gross monthly salary (inclusive of employee CPF contribution); last 12 months’ average
• Bonus: Typically last 2–3 years, averaged
• Variable income: Freelance, self-employed — usually averaged over 2 years
• Rental income: Counted if declared in tax returns

Income NOT counted:

• CPF Medisave or SRS top-up contributions
• CPF interest, investment returns, and retirement account balances
• Undisclosed or informal income

TDSR (55%) vs MSR (30%) — How They Apply

Private Property Loans

• TDSR ceiling applies: 55%
• MSR does not apply

HDB Resale Loans (Bank)

• Both TDSR (55%) AND MSR (30%) apply
• Bank loan for HDB resale must satisfy both ceilings
• New mortgage payment alone ≤ 30% of monthly gross income
• Total household debt ≤ 55% of monthly gross income

EC Purchases from Developer (Within 10 Years of TOP)

• Both TDSR (55%) AND MSR (30%) apply
• Same mechanics as HDB resale

Co-Borrower TDSR Calculation: Step-by-Step

Example: Couple Buying Private Property

Step 1: Sum all borrowers’ stable monthly income

• Primary salary: S$6,000
• Co-borrower salary: S$4,500
• Combined monthly gross: S$10,500

Step 2: Calculate total existing debt obligations

• Car loan: S$400/month
• Credit card commitment: S$100/month
• Personal loan: S$300/month
• Existing debt total: S$800/month

Step 3: Calculate proposed mortgage payment

• Loan amount: S$500,000
• Interest rate: 4.2% p.a.
• Tenure: 25 years
• Monthly payment: ~S$2,695

Step 4: Total debt after mortgage

• Existing: S$800
• New mortgage: S$2,695
• Total: S$3,495/month

Step 5: Check TDSR ratio

• Total debt / Combined income: S$3,495 / S$10,500 = 33.3%
• TDSR ceiling: 55%
• Result: APPROVED ✓

Example: Couple Buying HDB Resale (Bank Loan)

Same borrowers, same income (S$10,500), same debts (S$800), same mortgage (~S$2,695).

Check TDSR: S$3,495 / S$10,500 = 33.3% ≤ 55% ✓

Check MSR:

• New mortgage only: S$2,695
• MSR ceiling: 30% × S$10,500 = S$3,150
• S$2,695 ≤ S$3,150 ✓
• Result: APPROVED on both TDSR and MSR ✓

Critical Co-Borrower Stress Test Rules

MAS requires banks to conduct a stress test at MTIR floor of 4.0% p.a.:

• Bank uses the higher of 4.0% or the contracted rate
• If contracted rate is 4.2%, stress test uses 4.2%
• If contracted rate is 3.5%, stress test uses 4.0% (the MAS floor)

Stress test requirement: The combined household TDSR — using all co-borrowers’ income and all co-borrowers’ debt obligations — must not exceed 55% when computed at the MAS MTIR stress-test floor (4.0% p.a. or contracted rate, whichever is higher).

When Co-Borrower TDSR/MSR Fails

Approval fails if:

• Combined income is too low for target loan amount
• Co-borrower has existing high debt (multiple car loans, credit cards, other mortgages)
• Household debt servicing fails the stress test at MTIR 4.0% floor
• Co-borrower’s income is unstable (new job, contractual work) — bank won’t count it
• For HDB or EC: New mortgage alone exceeds 30% MSR ceiling

Common Co-Borrower TDSR Scenarios

Scenario A: Couple, First Private Property

Scenario B: Multi-Generational (Adult Child + Parent)

Scenario C: HDB Resale with Both Borrowers Holding Existing Mortgages

In Scenario C, MSR is not the limiting factor, but the high existing debt from the first mortgage leaves only S$2,675/month available for the second mortgage despite the 55% TDSR ceiling.

Key Checklist for CEA Agents

When a client mentions bringing in a co-borrower, always ask:

1. What is the co-borrower’s stable monthly income? (Salary, bonus, rental income)
2. What existing debt does the co-borrower have? (Car loan, personal loan, credit cards, other mortgages)
3. Is this HDB resale, EC purchase, or private property? (MSR applies only to HDB and eligible EC)
4. Has the bank approved a stress test scenario at MTIR 4.0% floor?

Co-borrower income can unlock larger loan amounts — but only if the combined household debt servicing passes both TDSR (55%) and, where applicable, MSR (30%) ceilings after stress testing.

Key Regulation

• MAS Notice 632 — Residential Property Loans: Governs co-borrower TDSR requirements and income counting rules for residential property loans
• TDSR ceiling: 55% (in effect since 16 December 2021)
• MSR ceiling: 30% (HDB bank loans and eligible EC purchases from developer within 10 years of TOP)
• MAS MTIR stress-test floor: 4.0% p.a. (since September 2022)