3-3-5 Rule Of Buying An HDB Flat: How Much Can Singaporeans Really Afford?  

Affordability remains one of the biggest concerns for HDB flat buyers in Singapore. Million-dollar HDB resale deals, once seen as exceptions, are now far more common, with 1,594 such transactions recorded in 2025.

As household incomes rise, buyers are naturally able to stretch their housing budgets. That can open the door to larger flats or homes in more convenient and desirable locations, but it also raises the risk of paying more than they can comfortably afford over the long term.

At the same time, a strong resale market and easing bank mortgage rates may tempt some buyers to take on larger loans. Recent reports show some bank home loan packages have fallen to around 1.55% to 1.8%, while the HDB concessionary loan remains at 2.6% per annum from 1 January to 31 March 2026.

Which leads to an important question: should affordability be based on the maximum amount we are allowed to borrow, or on what we can comfortably afford to repay?

Maybe not, if we use the 3-3-5 rule. This rule is a prudent approach to calculating housing affordability and is covered extensively by property blogger, Vina Ip (aka Property Soul).

First, what is the 3-3-5 rule about?

The 3-3-5 Rule 

The 3-3-5 rule has three conditions that you, as a flat buyer, must fulfill to determine the affordability of the home you intend to buy.

Pay 30% Of The Property Price 

The first condition is having enough cash and/or CPF Ordinary Account (OA) savings to cover the upfront costs of buying an HDB flat. As a practical rule of thumb, setting aside about 30% of the flat price gives buyers a buffer not just for the down payment, but also for buyer’s stamp duty, legal fees and other purchase-related costs. CPF OA savings can be used for the down payment, stamp duty, and legal fees, subject to prevailing rules.

For buyers using a bank loan, the minimum down payment is 25% of the purchase price, with at least 5% paid in cash and the remaining 20% payable using cash and/or CPF OA savings. For buyers using an HDB concessionary loan, the minimum down payment is also at least 25% of the purchase price. This can be paid using CPF OA savings, cash, or a combination of both.

In other words, while buyers may technically finance up to 75% of the flat price, the 3-3-5 rule suggests caution if you need to borrow more than 70% of the property’s value. Using that rule, a couple with a combined $120,000 in cash and CPF savings should cap their purchase budget at around $400,000, since $120,000 would represent 30% of the property value. This is a rule of thumb rather than a regulatory threshold.

For example, if a young couple’s combined cash and CPF balance is $120,000, then the maximum property value they can afford is $400,000 ($120,000/0.3).

Read Also: Understanding Loan-To-Value (LTV) Limit & Total Debt Servicing Ratio (TDSR) When Purchasing A Property In Singapore

Monthly Mortgage Servicing Of The Property Should Not Exceed 1/3 Of Your Monthly Salary

Second condition: buyers should not spend more than one-third of their monthly income on mortgage payments.

At present, the monthly mortgage servicing ratio (MSR) set by MAS for the purchase of HDB flats is capped at 30% of the borrower’s income.

This current requirement on financial institutions to ensure borrowers do not exceed the MSR supersedes the one-third condition.

For example, if the young couple’s combined gross monthly income is $8,000, their monthly mortgage should not exceed $2,400.

Read Also: Total Debt Servicing Ratio (TDSR) and Mortgage Servicing Ratio (MSR): How Much You Can Borrow When Buying An HDB Flat

Total Purchase Price Of The Property Should Not Exceed 5x Your Annual Income

The third and final condition is that the total purchase price of the property should not exceed five times the buyer’s annual income.

Whether the borrower uses a bank or HDB loan, their eligibility is determined by their age, income, and loan tenure. A young or high-income borrower may be allowed to borrow more than five times their annual income.

But when using the 3-3-5 rule, for example, a young couple earning a combined monthly income of $8,000 should not exceed $480,000 ($8,000 x 12 months x 5 years) for their property purchase.

Using The 3-3-5 Rule To Determine Affordability  

Now that we know what the 3-3-5 rule stands for, we shall use two examples to illustrate how it is applied.

John and Sarah are in their late 20s and are getting married this year. They are looking to buy their first house near Sarah’s parents. They have set aside $90,000 in cash and CPF funds to finance their property purchase and have a combined monthly income of $8,000.

Mr and Mrs Lee are in their mid-40s and are looking to upgrade to a bigger executive flat from their 4-room BTO flat. They expect to have $450,000 in sale proceeds to finance their next property purchase. Lastly, Mr and Mrs Lee have a combined monthly income of $13,000.

In the case of John and Sarah, they can only afford to purchase a flat for up to $300,000 due to their initial capital. Though their annual income might suggest they can afford a higher property purchase, their current capital does not support it. Young borrowers could be overleveraging by taking larger loans and longer loan tenors in the hope that their incomes will rise over time. However, if their circumstances deteriorate, they may find themselves saddled with a debt they cannot afford.

In the case of Mr and Mrs Lee, their borrowing capacity is limited by their income. Based on their combined income, their next property purchase cannot exceed $780,000.  Although their initial deposit is sufficient to purchase up to $1.5 million, their current monthly income does not support that purchase.

Home upgraders or couples with more capital may have a false impression that, given their larger down payment, their loan amount is small and manageable. This could lead them to inadvertently purchase a property beyond their income level.

From our two examples, we can see how and why flat buyers may unassumingly overstretch their budget. By taking a single favourable factor as their reference, they end up borrowing more than they should.

Are New BTO Flats Expensive For First-Timers?  

For most first-time homebuyers in Singapore, BTOs have been the property of choice. They are primarily viewed as an affordable option to owning a new property.

In a buoyant property market, the BTO flat prices have also risen in tandem, leading many to question the affordability level for first-timers.

When Telok Blangah Beacon was launched in 2021, the 4-room flats received approximately 10 times more applications from first-timers than other BTO launches. Which is surprising, given the minimum selling price without grants started at $602,000.

Hence, we ask how many first-timers could truly afford the BTO flat in Telok Blangah Beacon (excluding any grants), if the 3-3-5 rule is applied?

To answer this, we shall use a hypothetical example.

Assumptions:

• The couple are fresh graduates who have just started working in 2018.
• They are earning the same median salary of $3,500 each, based on MOM’s starting salary with an annual increment of $100.
• They will receive a 13-month (AWS) payment each year.
• They will save 10% of their gross monthly income in cash for the purchase of their first property.
• Calculations will be based on an approximate three-year accumulation of cash and CPF savings.

At the end of three years, the couple would have approximately $65,000 in their CPF Ordinary Account (OA) balance and $26,000 in cash.

Their combined monthly income in 2021 would be around $7,600. As first-timers, they may also qualify for $15,000 in enhanced CPF housing grants, which are income-based.

Next, let’s calculate the couple’s maximum affordability using the 3-3-5 rule, assuming they were to use their entire OA balance, cash savings, and CPF housing grants.

In this scenario, the maximum purchase price the couple can afford is $353,000. Hence, if they were to apply for the Telok Blangah Becon BTO, they could be overleveraging by two times.

In the same May 2021 BTO launch, first-time applicants had other relatively cheaper options in the non-mature towns of Tengah and Woodlands. The 3-room flats were priced between $330,000 to $345,000 while the 4-room flats were priced between $365,000 to $470,000.

This young couple could go for smaller-sized flats in non-mature towns or save up more for their downpayment to afford a flat closer to the $450,000 range that fits with the 3-3-5 criteria.

At the end of the day, we, as consumers, speak with our wallets. Conveniently located projects in mature towns do cost more and are probably out of reach for most young buyers. These groups of buyers should look for projects that are within their affordability range, even if that means picking smaller-sized units or projects in non-mature towns.

CPF Housing Grants Make Homes (Seem) More Affordable 

The government provides CPF housing grants to first-time flat buyers to assist with their home purchase. This can be up to $80,000 under the enhanced CPF housing grant for Built-To-Order (BTO) applicants and up to $160,000 (through enhanced CPF housing grant, family grant, and proximity grant) for resale flat applicants.

Flat buyers should view these grants as an additional buffer for emergency times rather than inflating their down payment and, thus, affordability. The use of grants to offset the purchase price could lead them to overleverage as their incomes may not support it.

Read Also: Complete Guide To HDB Housing Grants In Singapore For Different Types Of Flats

Most flat buyers are told to apply for their HDB loan eligibility (HLE) letter before they start their property search. In some ways, this could lead to an anchoring bias. And they may end up basing their selection on the maximum loan they can borrow, rather than considering an affordability perspective.

Hence, by starting with the 3-3-5 affordability test, we can make a more prudent assessment and avoid overfinancing our property purchase, as we have a larger buffer against unforeseen circumstances (such as interest rate hikes or job losses).

Read Also: Beginners’ Guide To HDB Loan Eligibility Letter (HLE) And How To Apply For It

The article was first written in 2022, and we have updated it with the latest information to reflect the higher down payment required for those taking an HDB concessionary loan