19/08/2026
📐 The "one-third of income" rule isn't law — and that's not a reason to drop it
Most agents screen affordability on the old rule that rent shouldn't exceed a third of income. It's a sound instinct, and you should absolutely be screening. But know what it is: a convention, not South African law. You won't find a one-third rule anywhere in the Rental Housing Act.
Where does it come from? US housing policy. A 1969 measure (the Brooke Amendment) capped public-housing rent at 25% of a tenant's income; it was lifted to 30% in the 1980s, and 30% became a widely used benchmark for "affordable".
Why it matters that it's a convention: it means nobody is checking your work but you. There is no statutory affordability test for a lease to hide behind — the standard you apply is the standard your landlord gets.
And a flat percentage is blunt in the direction that hurts. A tenant paying exactly a third can still be left short once debit orders and credit commitments come off. Passing the ratio is not the same as being able to pay the rent in month seven.
So use two passes, not one ratio:
• First pass — nett income at least 3× the rent. This is the gate: if an application doesn't clear it, there's little point processing it further.
• Second pass — for the ones that do, subtract statutory deductions, existing credit obligations and necessary monthly expenses. What's left is the applicant's discretionary income — the term used in affordability assessments under the National Credit Act. Ask the real question of that number: can this applicant comfortably afford the rent out of it? Not "does it technically cover the rent" — comfortably, with room for a bad month.
Worth knowing: South African law does have a proper affordability standard — it sits in the NCA and binds credit providers, not landlords. Which is exactly why the discipline in a rental application has to come from you.
An applicant who clears a third on paper but has almost nothing left once their commitments come off is exactly the tenant who becomes an arrears file. Screen on the discretionary income, not the gross.
Background (origin of the 30% rule): https://en.wikipedia.org/wiki/Brooke_Amendment
RentalSphere — we FOCUS on because
“Brooke Amendment” is the common name for section 213 (a) of the Housing and Urban Development Act of 1969 (Public Law 91-152) that was sponsored by Senator Edward Brooke III (R-MA), which capped rent in public housing projects at 25% of tenant's income. It amended section 2(1), paragraph two, o...
