A ruling by Greece’s Supreme Court has triggered unease across the country’s financial sector, raising concerns among loan servicers, banks, and the Public Debt Management Agency (PDMA). The court ruled that compound interest on restructured household loans under the so-called “Katseli Law” must be calculated on each monthly instalment rather than on the total outstanding principal.
According to a senior banker familiar with the matter, the implications of the ruling will depend heavily on the fine print once the full decision is formally published. The key issue, he said, is whether the judgment will apply retroactively—an outcome that could significantly amplify its financial impact.
For loan servicers, the decision threatens to reduce expected revenues from thousands of active restructuring agreements. The revised interest calculation method lowers projected cash inflows compared with those embedded in existing business plans, while also increasing legal uncertainty in the management of loan portfolios. There are growing concerns that borrowers may seek retroactive refunds for interest already paid under the previous calculation framework, potentially opening the door to new legal claims.
Banks, meanwhile, are primarily focused on the potential erosion of the value of these loans, whether they remain on balance sheets or have been transferred into securitisation structures. Lower expected collections undermine the assumptions underpinning securitisation transactions, increasing the risk of missing performance targets and placing pressure on loan-loss provisions and regulatory capital ratios. Some banking executives have described the ruling as a “global anomaly” and warn that, if extended to other types of loan restructurings, it could have broader implications for credit availability. As one senior banker put it, if credit growth slows in the coming months, “the reasons will be well understood.”
The PDMA is also closely monitoring developments, as the ruling affects the cash-flow assumptions of securitisations under Greece’s flagship “Hercules” programme, which was designed to reduce non-performing loans with the support of state guarantees. Reduced inflows from restructured loans raise the risk that senior bond repayment targets may not be met, potentially triggering government guarantees. Such a scenario would carry fiscal consequences, with a KPMG study estimating that the potential cost to public debt could reach as much as €1 billion.
Beyond its financial and legal ramifications, the ruling is expected to have a significant technological impact. For banks and servicers, it represents not a minor legal adjustment but a structural change that requires extensive modifications to core IT systems. The new interest calculation logic necessitates the redesign of algorithms, loan schedules, amortisation tables, and reporting frameworks, creating a new wave of demand for specialised IT services.
Core servicing systems, originally designed to calculate compound interest on total outstanding balances, must now be reprogrammed to accrue interest solely on individual monthly instalments. This shift requires fundamental changes to mathematical models and processing sequences. Reporting and management information systems must also be updated, as revised cash flows affect performance metrics, investor reporting, and supervisory disclosures. Particularly complex is the handling of historical data, as institutions must decide whether to recalculate interest on existing restructurings, a process that would involve large-scale recalculations and parallel tracking of old and new methodologies.
Customer-facing systems are also affected. Loan statements, borrower portals, and automated notifications must be updated to reflect the new calculation method with greater transparency, in an effort to reduce disputes and legal challenges. Finally, compliance and audit systems must be enhanced to clearly document when and how the new rules are applied, ensuring institutions can demonstrate adherence during regulatory reviews or court proceedings.
