France's 2014 Hamon decree liberalised prospecting; Belgium's ITAA still bans it. Twelve years on, which channels actually build a client base for an accounting firm? This guide reviews the four methods that work, explains why cold email alone fails structurally rather than legally, and clarifies the France-Belgium legal landscape after the CNIL's 10 June ruling and the 11 August 2026 telephone reform (consumer-only).