For buyers contracting authority
Reach for 72232000 when the system you are commissioning is built around transactions: collecting money, settling charges, processing filings, moving records through a controlled workflow. The income-collection, ERP and tolling examples below are the typical shape. The deliverable is bespoke working software, accepted against your specification, not a packaged product configured to fit.
The boundary that trips authorities is the parent and the generic build code. Custom software development services (72230000) is the broader bucket; choose the more specific 72232000 when transaction processing is genuinely the heart of the system. General-purpose bespoke development with no transaction core points to Software development services (72262000) instead.
Where a single contract bundles the build with the maintenance that follows, or with licences for components it sits on, set the primary CPV code by the dominant spend rather than by the whole package.