What Is Income Weighted Average Age (IWAA)?
The income-weighted average age (IWAA) is used to calculate the average age of joint borrowers for residential housing loans in Singapore. A greater weightage is given to the person(s) with higher income(s). Therefore, if an older borrower earns more, the IWAA will be higher than the simple average age. Conversely, If the younger borrower earns more, the IWAA will be lower than the simple average age.
The formula relates to the individual's ability to repay the loan and helps determine the "effective age" of joint-borrowers.
When was IWAA introduced?
29 June 2013.
This was introduced along with the Total Debt Servicing Ratio (TDSR). More information on TDSR can be found here.
Why is IWAA Important?
Before the introduction of the Income-Weighted Average Age (IWAA) in 2013, banks and financial institutions were allowed to assess joint loan applications based on the combined income of joint borrowers while using the age of the younger borrower.
This created a major loophole. In order to qualify for larger loan amounts and extended loan tenures with the younger age factor, high-income individuals could include their adult children as joint borrowers for a housing loan. Large amounts of financing that could potentially stretch the borrowers' repayment capacities could then be secured.
As such borrowing contributed to soaring property prices, the MAS then introduced TDSR and IWAA - which is a more accurate reflection of financial capacity - in a bid to stabilise the market and encourage financial prudence.
How IWAA affects your loan tenure?
Banks use the Interest-Weighted Average Age (IWAA) to determine your effective age when assessing how long your home loan tenure can be. Instead of taking each borrower’s age individually, IWAA blends the ages of all applicants based on how much each person contributes to the monthly instalment.
This matters because your loan tenure is capped by MAS rules:
- Maximum home loan tenure: 35 years for private or 30 years for HDB
- Tenure may be reduced if the IWAA exceeds 35, or if the loan would extend past the borrower’s age limit (usually age 65 depending on bank policy)
Specially for HDB purchases, IWAA works together with MSR, LTV limits, and CPF usage rules to determine how much you can borrow. A higher IWAA (older effective age) generally means:
- A shorter loan tenure
- Higher monthly instalments
- A lower maximum loan amount
If you’re buying an HDB flat, you can refer to our HDB Home Loan Guide to understand how IWAA interacts with MSR, LTV, CPF rules, and other HDB-specific eligibility factors.
How is IWAA calculated?
Assuming 2 borrowers (B1 & B2) with total gross monthly income I the formula to calculate IWAA is:
IWAA = (B1's Age x B1’s gross monthly income)/I + (B2’s Age x B2’s gross monthly income)/I
>> You do not have to calculate it manually. Head to our IWAA calculator instead!
For example, Mr Lim is 58 years old and has a gross monthly income of $12,000. His son, Leo, is 28 years old and has a gross monthly income of $8,000. Their IWAA is therefore:
(58x$12,000/($12,000+$8,000)) + (28*$8,000/($12,000+$8,000))
= 34.8 + 11.2
= 46 years old
Their IWAA of 46 years old is then used to determine their loan tenure, loan amount, as well as their monthly loan instalments.
Income Weighted Average Age (IWAA) Calculator
Based on 2 joint borrowers and their respective monthly incomes.
*Calculator results are estimates only. The IWAA calculation is based on the income-weighted average age formula referenced by MAS. Users should refer to MAS guidelines and check with the relevant bank or financial institution for the final assessment.
Do You Know?
Your IWAA determines your loan tenure, and this will impact your monthly mortgage for your desired property? Also, your eligible Loan-to-Value (LTV), determines how much cash / CPF you are required to fork out as downpayment. As each person's circumstance is unique, speak to us to find out your optimal loan parameters.
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