What it means
The two numbers do different jobs. The 28% test, often called the front-end ratio, looks only at housing, while the 36% test, the back-end ratio, looks at housing plus every other regular debt payment.
Housing costs for this purpose mean more than the mortgage payment. They normally include principal, interest, property taxes, building insurance and any compulsory association or service charge, because all of those must be paid to keep the home.
The back-end test adds car loans, student loans, personal loans, minimum credit card payments and any court-ordered payments such as maintenance. It deliberately excludes discretionary spending like groceries and utilities, which is one reason it is a screen rather than a full budget.
Both ratios use gross income, meaning income before tax and deductions. That matters because a household in a high tax area has far less take-home pay behind the same gross figure, so passing the test does not by itself prove the payments will feel affordable.
Lenders apply the rule as a guide and will stretch it where there are offsetting strengths, such as a large deposit, substantial savings or a long record of handling a similar payment. Equally, they tighten it where income is variable, which is why self-employed applicants are usually assessed on an average of several years of declared income.
The practical nuance is that one of the two tests always binds first. Working out which one it is tells a borrower exactly what to fix, because clearing a car loan raises borrowing capacity only when the back-end test is the binding constraint.
In practice
Real-world examples.
Example
A couple earning $9,000 a month between them are pre-assessed by a credit union. Their $2,520 housing limit and $520 of taxes and insurance leave $2,000 for principal and interest, which sets a realistic price range before they start viewing properties.
Example
A self-employed consultant reports $14,000 a month in a strong year, but the lender averages three years of declared income to $8,500. Her housing limit falls from $3,920 to $2,380, so she adds $40,000 to her deposit to bring the required payment inside the test.
Example
A relocating manager fails the back-end test by $180 a month because of a car lease. He settles the lease before applying, which removes $540 of monthly debt and moves the binding constraint back to the 28% housing test.
Formula
Calculation
Front-end limit = gross monthly income x 0.28 and Back-end limit = gross monthly income x 0.36
Take a household with gross income of $108,000 a year, which is 108,000 / 12 = $9,000 a month. The front-end limit is 9,000 x 0.28 = $2,520 for all housing costs. The back-end limit is 9,000 x 0.36 = $3,240 for housing plus other debts. If the household already pays $420 on a car loan, $180 on a student loan and $100 in card minimums, that is $700 of other debt, leaving 3,240 - 700 = $2,540 available for housing under the back-end test. The binding limit is the lower of $2,520 and $2,540, so $2,520, and if property taxes and insurance come to $520 a month the household has 2,520 - 520 = $2,000 a month for principal and interest.Case study
Seen in the real world.
Pinefield Credit Union is an illustrative, fictional lender that reviewed why first-time buyers were abandoning applications late in the process. It found that applicants were being told a borrowing figure based only on the 28% housing test, then being declined weeks later when car and student loans pushed them through the 36% ceiling.
The lending team rebuilt the first conversation around both tests at once. Staff now calculate the two limits side by side and tell the applicant which one binds, so a buyer with $700 of other monthly debt hears a housing figure of $2,520 and the reason behind it on the first call.
Abandoned applications fell sharply and complaints about late declines mostly stopped. The illustrative point is that the rule works best as a planning tool shared with the borrower, not as a hidden gate they discover only when the answer is no.
Watch out
Common mistakes.
- Using take-home pay instead of gross income, which makes the limits look much smaller than the ones a lender will actually apply.
- Counting only the mortgage payment as housing cost and leaving out property taxes, insurance and compulsory service charges.
- Treating the rule as a legal cap, when lenders routinely stretch it for applicants with large deposits, strong savings or a proven payment record.
Questions
People also ask.
What counts as debt in the 36% test?
Regular contractual payments such as car loans, student loans, personal loans, minimum card payments and court-ordered maintenance, but not groceries, utilities or other discretionary spending.
Can I still borrow if I fail one of the tests?
Often yes, because many lenders will go beyond these ratios where there are compensating strengths, though the pricing or the deposit requirement may be less favourable.
Which ratio should I try to improve first?
Work out which one binds, since clearing other debts only helps if the 36% test is the constraint, whereas a larger deposit is what helps when the 28% test binds.
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