You've found a property you like. It's listed at R1.8 million. You earn a decent salary, pay your accounts on time, and you've been saving for a deposit. But when you ask a colleague what the bank will lend you, the answer is usually some version of "three times your salary" or "about 30% of your income."
Both rules of thumb exist for a reason. Neither tells the full story. And if you're going into a bond application relying on them, you may be in for a surprise.
Here's how banks actually calculate what they'll lend you, and what you can do to improve that number before you apply.
The figure that matters most is not your salary
Banks don't lend based on your gross income in isolation. They lend based on your net surplus income: what remains after your tax, your existing debt obligations, and your living expenses have all been subtracted.
This calculation is not optional. It is required by law.
The National Credit Act obliges every registered lender to conduct an affordability assessment before approving any credit agreement. A bank that approves a bond without properly assessing your ability to repay is legally guilty of reckless lending. The framework exists to protect you as much as the bank.
In practice, it means two people on the same gross salary can be offered very different bond amounts, depending entirely on what each of them owes and spends every month.
The 30% rule: useful, but just a starting point
The most commonly cited guideline is that your total monthly debt repayments shouldn't exceed 30% of your gross monthly income — including the bond repayment you're applying for. If you earn R50,000 gross per month, all your debt commitments combined should sit at or below R15,000 per month.
Reasonable starting point. But just that.
Banks also look at your net disposable income after real living expenses: food, transport, utilities, school fees, insurance, medical aid, and anything else that goes out regularly. If your living costs are high relative to your income, the bank may offer you less than the 30% guideline suggests, even if your debt level is technically within that band.
Absa applies the 30% threshold as a guide rather than a hard ceiling, assessing each application on its merits. FNB weighs living expenses alongside credit commitments. Each major bank uses its own methodology, which is one reason applying to multiple lenders often produces meaningfully different offers.
The five things every bank looks at
1. Your gross and net income
The bank wants to see your gross salary (before deductions) and your net salary (what actually arrives in your account). If you earn commission, rental income, or freelance income, banks will typically average this over 6 to 12 months rather than taking any single month at face value. Variable income isn't disqualifying, but it needs to be consistent and verifiable.
2. Your existing debt commitments
Car repayments, personal loans, credit cards, store accounts, student loans: all of it is counted. The bank pulls a credit bureau report and checks your declared commitments against it. Anything missed or understated will be visible. The key number is how much of your income is already committed before the bond repayment is even added.
3. Your credit profile
Your credit profile is compiled by one of the major bureaus: TransUnion, Experian, or XDS (also known as Compuscan). Each uses its own scoring scale and methodology, so your score will differ between them. A TransUnion score doesn't translate directly to the same number on Experian. There's no single universal target.
Banks don't simply read off a bureau score and approve or decline on that basis. They use the bureau report as one input into their own internal credit assessment models, which weigh your repayment history, current debt levels, any defaults or judgements, and recent credit enquiries. Your past relationship with a specific bank may also factor in.
As a broad guide, most banks look for a minimum bureau score of around 600 to 640 before considering a home loan application, though this threshold varies by lender. A stronger profile improves both your chances of approval and the interest rate you're offered. A weaker profile doesn't automatically disqualify you, but it will likely affect the terms you're approved on.
What the bureau report and the bank's own model are really looking for is the same thing: evidence that you pay your commitments consistently and on time. That underlying behaviour drives both your bureau score and a bank's confidence in you as a borrower.
Your credit profile affects not just whether you're approved, but what interest rate you're offered. That rate, in turn, affects how large a bond the same monthly repayment can service. A difference of 0.5% in your interest rate can shift your approved bond amount by tens of thousands of rands.
4. Your deposit
A deposit reduces the bank's risk. Put down 10% or more, and the bank is lending at a lower loan-to-value ratio, which typically produces a more competitive interest rate and improves your approval chances.
That said, 100% bonds remain available for qualifying applicants. In Q3 2025, 56% of home loans accepted through ooba Home Loans were at 100% loan-to-value or higher, up 5% on the same period the previous year. A deposit helps, but not having one doesn't automatically rule you out.
5. Your employment stability
Most banks require permanently employed applicants to have been in their current role for at least six consecutive months. If you're self-employed, the requirement is typically two years of verifiable, profitable business activity, along with six months of personal bank statements rather than the standard three.
How the bank builds the number
Once the bank has your income, expenses, debts, and credit profile, it calculates the maximum monthly repayment you can service. That maximum repayment is then worked backwards through the current interest rate and loan term (most commonly 20 years) to arrive at a maximum bond amount.
At a prime lending rate of 10.25% over 20 years, a monthly repayment of R10,000 services a bond of approximately R1,018,000. A repayment of R15,000 per month services roughly R1,528,000. These aren't exact figures — they shift with rate changes and your personal interest rate, which may be above or below prime depending on your profile.
The interest rate you're actually offered is priced relative to prime. In Q3 2025, ooba Home Loans secured an average rate of prime minus 0.69% for its clients. Banks compete actively for home loan business, and your own bank's offer isn't always the best available.
The gap between what you expect and what you get
The most common reason a bond application comes back lower than expected is existing debt. A car repayment of R6,000 per month and a credit card with a R3,000 minimum payment consume R9,000 of whatever monthly capacity the bank is willing to allocate. In a 30% affordability calculation on a R50,000 gross income, that leaves R6,000 for the bond repayment, which services a bond of roughly R611,000. The same person with no existing debt, using the full R15,000 monthly capacity, could be approved for around R1,528,000 — more than double.
The other common surprise is the interest rate. If your credit profile is average rather than strong, the bank may offer you prime plus 1% rather than prime minus 0.5%. On a R1.5 million bond over 20 years, that difference works out to roughly R1,500 extra per month and over R360,000 in additional interest across the life of the loan.
The pre-qualification advantage
Getting pre-qualified before you start looking at properties is genuinely useful, not just a formality.
Buyers who completed pre-qualification before applying through ooba Home Loans achieved a 91% approval rate in Q3 2025, compared to an overall average of 83.9%. Pre-qualification gives you a realistic ceiling to work within, surfaces any credit issues you can address before formally applying, and makes your offer more credible to a seller.
It also means that when you do find the right property, you're not scrambling to get a bond in place while the clock runs on an offer to purchase.
Something most buyers don't think to ask about
Applying to a single bank is not necessarily your best move.
In Q3 2025, 48.6% of home loan applications declined by one bank were subsequently approved by another. That figure alone makes the case for applying to multiple lenders — either directly or through a bond originator who submits to several banks simultaneously at no cost to you.
The differences between offers aren't trivial. Interest rate concessions vary. Loan-to-value ratios vary. Some banks will accommodate specific property types or income structures that others won't. Comparing offers takes very little additional effort and can materially affect the cost of your bond over its lifetime.
What you can do right now
Before you speak to a bank or a mortgage adviser, run your own affordability numbers privately. Knowing your gross and net income, what your existing debts cost you monthly, and what a realistic bond repayment looks like at current rates puts you in a far stronger position when the formal conversation starts.
It turns "I think I can afford about R1.8 million" into "here's exactly what I can service, here's what I should clear before I apply, and here's the deposit that will get me the best rate."
That's the version of you a bank wants to see.
Zettl's buyer affordability calculator shows you what the banks will typically lend at your income level, based on your gross income and existing debt commitments. Free, instant, no sign-up required.