Explain an AP-to-SAP career switch as a four-part story: the Accounts Payable work you understand, the reason SAP is a logical extension of that work, the SAP knowledge and practice you have deliberately added, and the kind of entry role you can credibly perform next. Keep the story specific, evidence-based and free of invented implementation claims.
Start with the business process, not the career change
Describe the AP responsibilities that built your foundation: supplier invoices, exceptions, approvals, payment readiness, reconciliation, period-end work or procure-to-pay coordination. This gives the interviewer a concrete starting point and shows that your domain knowledge is useful rather than something you are abandoning.
Explain why SAP follows naturally
A strong reason is usually about scope: you want to understand how the process is represented, controlled and integrated in an ERP system, and eventually help improve that process. Avoid vague answers such as choosing SAP only because it is popular or because you want a technology job.
Prove that the transition is already underway
Point to concrete learning evidence: process maps you can explain, SAP concepts you can connect to AP, testing examples, a transition portfolio, or structured practice scenarios. Be explicit about what is learning evidence and what comes from your professional AP experience.
Finish with realistic role fit
Show that you understand the difference between domain experience and SAP project experience. A sensible target may be a junior functional, finance-systems, support, testing or process role where AP knowledge is valuable and SAP depth can grow. That is stronger than claiming immediate senior-consultant readiness.
Continue with Build a Transition Portfolio, Which AP Skills Transfer?, Skills Gaps to Close and the Careers & Career Switching hub.