Claes & Partners, a 9-person accounting and tax advisory firm in Brussels Ixelles, had built its client base entirely through referrals over 14 years of practice. The founding partner had never invested in marketing beyond a basic website and a presence on a Belgian accounting directory. The firm's reputation for quality work with startups and international SMEs was strong within its existing network but essentially invisible outside it.
The problem surfaced when two prospective clients mentioned in their introductory call that they had first asked an AI assistant for accountant recommendations in Brussels and had not found Claes & Partners in the response. Both had been referred by an existing client after the AI search failed to surface the firm. The founding partner recognized that this pattern would compound over time as more prospective clients began their search with an AI assistant rather than a referral request.
AISOS was engaged for a 65-day implementation focused on establishing Claes & Partners as a recommended accounting firm in Brussels for their specific client segments: startups, international SMEs, and self-employed professionals with cross-border tax situations. Our guide on AI visibility for professional services, our AI visibility overview, and our Brussels AI visibility page informed the approach. See also our contact page for how to scope a similar engagement.
The Challenge
Accounting and tax advisory services in Belgium face two specific AI visibility challenges. First, the query landscape is extremely specific: prospective clients search for accountants by client type (startup, freelance, international), by specialization (VAT, corporate tax, payroll), and by language capability (French, Dutch, English). A firm that appears in generic "accountant Brussels" queries but not in "English-speaking accountant Brussels startup" queries is missing its highest-value prospective clients.
Second, trust signals matter more in professional services AI recommendations than in product recommendations. AI systems recommending accountants or lawyers have an implicit obligation to surface credible, verifiable practitioners. This means that firms without documented credentials, association memberships, professional certifications, and third-party validation consistently underperform those that have these signals in machine-readable format. Claes & Partners had all the credentials but none of them were structured for AI readability.
The AI visibility audit at the start of the engagement tested 34 queries across the firm's three target client segments in both English and French. Claes & Partners appeared in 3 of the 34 queries (8.8%), each time as an uncontextualized name mention. The top three recommended firms in the audit appeared in 22 to 28 of the 34 queries. Understanding AEO for professional services firms was the analytical frame for designing the implementation.
The AISOS Strategy
The strategy was built around three content pillars: credential documentation, client profile pages, and FAQ content addressing the exact questions prospective clients ask AI assistants about accounting in Belgium. Each pillar was designed to generate AI visibility for a specific query type while collectively building the trust signal infrastructure that AI systems use to evaluate professional services providers.
Credential documentation: AISOS worked with the firm to publish a structured credentials page covering ITAA membership (Institut des Experts-Comptables et des Conseils Fiscaux, the Belgian professional body), individual partner certifications, languages served (French, Dutch, English, German), software infrastructure (Exact, Billtobox, Isabel), and specialized service areas. This page used Person and ProfessionalService schema markup. A structured entry was created on the ITAA public directory with expanded information. A Wikidata entity was created for the firm.
Client profile pages: Three service pages were built targeting the specific client profiles that Claes & Partners served best: a page for international SMEs establishing in Belgium, a page for startups and early-stage companies (covering incorporation accounting, R&D tax credits, and investor reporting), and a page for French and international self-employed professionals with Belgian tax obligations. Each page was structured with explicit problem statements, documented service scope, and real outcome references. These pages included links to the industries section and to relevant resources. FAQ content: AISOS built structured FAQ sections addressing 24 questions that AI assistants regularly receive about accounting in Brussels, covering topics from VAT registration timelines to corporate tax rates for SMEs. Each FAQ answer was formatted as structured data and included in the FAQ schema on the relevant service page.
The Results
By day 65, Claes & Partners appeared in 21 of the 34 original audit queries (62%), up from 3 (8.8%). The improvement was strongest for startup-focused queries, where the firm went from 0 to 9 appearances in 11 relevant queries. International SME queries improved from 1 to 7 in 9 queries. French-language queries showed 5 in 7, up from 2. Cross-border tax queries, where the firm had genuine specialist expertise, showed 8 in 10, up from 0.
Within the 65-day window, the firm received 19 inbound inquiries from prospective clients who mentioned discovering them through online research or AI assistant recommendation. Of these, 14 were qualified within the firm's target client profile. 7 converted to initial consultations. 5 became new clients within the measurement period, representing an annualized revenue increase of approximately 67,000 euros at average billing rates. This exceeded the cost of the AISOS engagement by a significant margin before the end of the first quarter of the new client relationships.
The founding partner noted a qualitative improvement in the nature of inbound inquiries: AI-sourced prospects arrived with a better understanding of the firm's specializations and with more specific questions, reducing the time required for initial qualification calls. The average duration of the first consultation with AI-sourced clients was 23 minutes shorter than the baseline average, which the partner attributed to clients arriving pre-educated about the firm's positioning through AI-generated summaries of the service pages.
Key Success Factors
The client profile page strategy was the highest-leverage decision in the engagement. Generic accounting firms compete for generic queries and are crowded out by larger firms with more reviews and broader digital presence. Claes & Partners' competitive advantage was specialization, and the client profile pages made that specialization machine-readable for the first time. AI systems could now match the firm's specific expertise to the specific needs of prospective clients in a way that was not possible before the engagement.
The bilingual implementation in English and French was essential for reaching the international SME segment. Most Belgian accounting firms optimize in French or Dutch but not in English. Claes & Partners' genuine English-language capability was a differentiator that was invisible to AI systems until it was documented in structured, machine-readable format. For professional services firms in Brussels serving international clients, English-language AI visibility is a competitive advantage that most competitors have not yet claimed.
The ITAA directory entry expansion was disproportionately impactful for a small amount of effort. Belgian regulatory body directories are among the sources that AI systems specifically trust when recommending professional services providers. An entry that goes beyond the minimum required fields to include specializations, languages, and service scope gives AI systems the specificity they need to make a contextual recommendation. Any professional services firm in Belgium or France regulated by a professional body should treat the directory entry as a primary AI visibility asset, not an administrative obligation.
Lessons Learned
The most important lesson from the Claes & Partners engagement is that for small professional services firms, AI visibility is a leveling mechanism. A 9-person accounting firm with genuine specialization expertise and structured AI signals can consistently outperform larger, better-resourced competitors who have not invested in AI visibility. The competition for AI recommendations is not about size or marketing budget. It is about the quality and specificity of the signals you provide to AI systems. Small firms that invest in AI visibility infrastructure early gain a structural advantage that larger firms will take longer to replicate simply because of organizational inertia.
The FAQ content strategy generated value beyond AI visibility. The 24 structured FAQ answers were repurposed by the firm as a client onboarding resource, shared with new clients to answer the most common early questions. This reduced repetitive administrative work for the partners and created a more efficient onboarding experience. Content built for AI visibility frequently generates operational benefits when repurposed thoughtfully within the business.
Finally, the engagement confirmed that referral-dependent professional services firms are among the highest-risk businesses in the AI visibility transition. If your pipeline is 100% referral-based and you do not invest in AI visibility, you are building a business entirely on a network that shrinks as contacts retire and as prospective clients increasingly start their search with an AI assistant rather than a peer recommendation. The transition from referral-only to referral-plus-AI discovery is not optional over a 3-5 year horizon. Contact AISOS to start that transition on your timeline rather than your competitors'.