Why openness tends to help
Clients rarely expect an accounting firm to write its own software, just as they do not expect it to build its own office. What they want to know is that the firm chose the tools deliberately, controls their data and stands behind the results. A short, honest explanation answers those concerns before they turn into doubts.
Trouble tends to come from implying something untrue, such as claiming your firm engineered the platform. If a client later discovers the vendor, the issue is the implication, not the arrangement. Describe the software as your firm’s service, built on a platform you selected and manage.