South African credit scores are produced by four main bureaux: TransUnion, Experian, XDS and Compuscan. The principles for improving your score are similar across all of them.
Payment history is the largest single factor. A single missed payment can drop your score by tens of points; a string of them does serious damage. Set debit orders for the day after payday so accounts are paid before you spend.
If you have arrears, the fastest way to lift your score is to settle them. After payment, ask the credit provider to instruct the bureau to update your status. Bureaux must act on instructions promptly.
"Utilisation" — how much of your available credit you are using — is a major factor. Keeping balances below ~30% of the limit is much better than running them at 90–100%, even if you pay in full.
Every formal application triggers an "enquiry" on your bureau record. Many enquiries in a short period signal financial stress and lower your score. Use comparison tools (which don't pull a hard enquiry) to narrow down before applying.
South African law gives you the right to one free credit report per bureau per year. Check it. Errors are common — wrong names, accounts that aren't yours, settled debts still marked open. Dispute errors in writing; the bureau must investigate within 20 business days.
If you have no credit history, a small account paid reliably (e.g. a low-limit credit card or mobile contract) builds positive data. After 6–12 months of on-time payments, your score improves noticeably.
Negative information stays on your report for set periods under the NCR rules — typically 1 to 5 years depending on the type. The clock runs whether you check the report or not, so old defaults will fall off over time provided no new ones are added.