UK Enterprises Urged to Consider C# as Primary COBOL Migration Target in 2026

A growing number of UK banks, insurers, public sector bodies, and retailers still rely on legacy COBOL systems, many of which have been running for decades. As COBOL expertise retires from the workforce, organisations face increasing pressure to modernise their core systems. C# on .NET is emerging as a preferred migration target, particularly for organisations already using Microsoft infrastructure, largely due to its native 128-bit decimal type that handles exact financial arithmetic without third-party libraries. Three main migration approaches exist — automated conversion, parallel rewrite, and incremental strangler-fig migration — each carrying different cost and risk profiles, with most UK enterprises opting for a hybrid method. A mid-sized COBOL-to-C# migration typically costs between £200,000 and £800,000 and takes one to two years, with underestimating project scope identified as the most common reason for failure.