Accounts Payable Specialist for Venture-Backed Startups | QBO, Bill.com, Ramp

OVERVIEW Alta Advisors is a strategic finance and accounting firm serving venture-backed startups in deeptech, hardtech, and applied AI. We act as an embedded accounting and finance partner to technically sophisticated companies and are looking for an experienced Accounts Payable Specialist to support AP operations across multiple startup clients. This is a part-time, ongoing, client-facing role for someone with strong AP fundamentals, hands-on QuickBooks Online experience, and familiarity with tools like Bill.com, Ramp, and Brex. You will own routine AP workflow across multiple clients, communicate directly with clients and vendors, and work closely with Alta’s accounting team to keep processes moving with accuracy, professionalism, and good judgment. We are specifically looking for someone with prior experience in a CAS, outsourced accounting, bookkeeping, or similar client-service environment who has supported at least 5 client accounts simultaneously. The right candidate can context switch across different workflows, personalities, and company operating styles while staying organized, responsive, and aware of when to escalate issues to a client controller, senior accountant, or other Alta team members. WHAT YOU'LL DO - Own day-to-day AP workflow across multiple client accounts - Review, code, and process vendor invoices for accuracy, completeness, and proper support - Route invoices for approval and follow up to keep the process moving - Prepare ACH, check, and card payments for approval and processing - Maintain vendor records, W-9s, 1099 tracking, and consistency between AP systems and related QBO records - Communicate professionally with clients and vendors on routine AP matters - Review AP aging and proactively flag overdue items, exceptions, or risks - Escalate non-routine issues, disputes, or coding questions to the appropriate Alta team member - Collaborate with the Alta accounting team on client deliverables, process consistency, and workflow improvement - Maintain organized, audit-ready support for AP transactions REQUIRED EXPERIENCE - 3+ years of hands-on accounts payable experience - Strong QuickBooks Online experience. This is a hard requirement - Experience with Bill.com, Ramp, Brex, or similar AP/spend management tools - Prior experience in a CAS, outsourced accounting, bookkeeping, or similar client-service environment - Experience supporting at least 5 client accounts simultaneously - Ability to work independently, stay organized, manage recurring workflow, context switch effectively, and know when to escalate - Strong written English and professional communication skills - Experience handling confidential financial information with professionalism and discretion - Reliable availability during US business hours - Willingness to provide 2 to 3 professional references as part of the screening process PREFERRED - Experience supporting venture-backed startups or other fast-moving businesses - Experience working in multi-system client environments with AP, spend management, and accounting workflows - Experience working with distributed remote teams - Familiarity with 1099 tracking, year-end preparation, or filing support WORKING RELATIONSHIP This is a part-time contract role expected to average 20 to 35 hours per week. The role is fully remote and will support multiple Alta startup clients over time.