When a lender assesses you, it is really asking one question: how likely is this money to come back? A weak or thin credit record, an income that fluctuates, or a business with no trading history all push that answer in the wrong direction. A loan guarantee changes the arithmetic. Somebody else – a person or an institution – signs an undertaking that if you stop paying, they will pay. The lender now has two places to recover from instead of one, and can approve an application it would otherwise decline.
It is worth separating a guarantee from collateral. Collateral is an asset the lender can attach and sell: a house behind a bond, a vehicle behind a finance agreement. A guarantee is a promise backed by another person's income and estate, not by one specific asset. That makes it useful precisely where collateral is missing – a first job, a start-up, a student – and it also means the guarantor is exposed across everything they own, not just one item they agreed to put up.
South African law treats this seriously. A suretyship must be recorded in writing and signed by the surety to be enforceable, and where the guaranteed debt falls under the National Credit Act, the guarantee is classified as a credit agreement in its own right. The guarantor therefore gets the Act's protections – disclosure, an affordability assessment, notice before legal steps – and carries its consequences, including a listing at the credit bureaux if things go wrong.