South African corporate treasurers have a new acronym to learn, and unlike most regulatory changes, this one comes with an actual hard deadline attached. From 31 December 2026, South Africa will stop publishing the Johannesburg Interbank Average Rate, better known as Jibar, and from 1 May 2026 no new Jibar-linked contracts may even be created. Its replacement, the South African Rand Overnight Index Average, or Zaronia, is already carrying more than R200 billion of exposure, up sharply from R6.4 billion a year earlier, according to Rashad Cassim speaking at the MPG Conference 2025.
Why this is a bigger deal than swapping one number for another
Jibar was a forward-looking rate, published at the start of an interest period so everyone knew the number in advance. Zaronia is backward-looking, an overnight rate built from actual transactions and published by the South African Reserve Bank after the fact. That single structural difference means every coupon, reset, notice and payment tied to a floating-rate instrument now depends on data that has to be verifiable, auditable and reproducible in a way the old system never demanded, since there was never anything to verify against, the rate was simply published upfront.
A Moneyweb opinion piece frames the real risk plainly: many organisations still manage debt administration through spreadsheets, chase approvals through email inboxes, and rely on a handful of staff who hold the institutional memory for how it all actually works. That informal setup may have been perfectly adequate when benchmark conventions were simple and static. It becomes considerably harder to defend under the scrutiny investors, lenders and auditors now expect, especially once a benchmark switch means the underlying calculation itself has changed shape.
The scale here is not small. Cassim estimated domestic Jibar-linked exposure at about R43 trillion in mid-2025, with offshore exposure exceeding R107 trillion, figures that make clear this transition is already moving through the financial system at genuine scale rather than sitting as a future problem. An undocumented spreadsheet formula or a missed email approval, trivial on any ordinary day, could plausibly become a market confidence issue once multiplied across exposure of that size.
The recommended fix is organisational as much as technical: separate the roles of data sourcing, calculation, validation and payment execution, and build an automated audit trail showing which data source was used, who checked the numbers, what approvals applied and when investor notices went out. That is not merely a compliance box to tick, it is a market credibility upgrade that can genuinely affect pricing, appetite and trust in an issuer’s paper.
While the reporting here focuses on large corporates, the same principles reach smaller firms with bank loans or bonds tied to Jibar. SMEs still running interest calculations through manual spreadsheets will need to consider similar upgrades to their own processes if they want to maintain lender confidence once the benchmark switch is complete. The global move away from Libor showed the same pattern: benchmark reform forces institutions to confront data quality, system controls and accountability all at once, and South Africa is now squarely in that implementation phase, where treating Zaronia as a simple deadline rather than an operating-model overhaul risks missing the point entirely.
There is a genuine silver lining buried in a transition this disruptive, which is that it forces exactly the kind of housekeeping many treasury functions have quietly needed for years regardless of the benchmark switch. A company that builds a properly automated, auditable process for Zaronia compliance ends up with better financial controls generally, not just better Zaronia controls, the same way a business that overhauls its books for one regulatory deadline usually finds the improved process pays off well beyond that specific requirement. Treasurers who treat this purely as a box-ticking exercise before the deadline are, in that sense, leaving value on the table twice over.
