Client Billing Coordinator

About us

At Moon Rabbit, growth isn't just a goal—it's a reality. We're expanding our core business with a team of remarkable talent, driving us forward every day. Our partnerships span a diverse range, particularly in healthcare, where we collaborate with leading industry names and innovative startups alike. Beyond healthcare, we’re proud to work with organizations committed to advancing society and making a lasting impact. Together, we’re shaping a better future.

We’re Blended – we’ve mixed some of the very best people in healthcare with people who have done their most stellar work in consumer. We have discipline and imagination in equal measure. We have PhDs and high school dropouts, media-first digital natives and old school idea-first strategists. We're a giant bag of cultures, beliefs, and backgrounds that make a beautiful sound when they play together.

We’re Bright – the work might look effortless, but the thinking that shaped it is really smart. We’re constantly on the lookout for the real problem, the real opportunity, the thing that, if solved, will change things. We work hard to get intimate with the areas we are playing in because there’s no meaningful insight without intimacy.

We're in search of Brilliant – our formula for success is simple. Bring a diverse bunch of brilliantly talented, collaborative, interesting people together. Give them the tools that they need to do their jobs. Treat them right, pay them right, give them a stake in success, and watch the business fly.

What we’re looking for in you

• Be You – bring yourself to work and to the work that you do.
• Be Ambitious – bring a desire to excel and to win, a desire to push yourself and your teammates to create the very best work, and fight for the work you believe in.
• Be Curious – dig deep and outright care more. Don't ask if it's good enough, ask if it's great enough.
• Be Invested – in your clients’ success, sweat the small things and behave as partners, not providers.
• Be Collaborative – we’re a group of people all on the same path, looking to do things better (and do better things), together.

If all of that sounds like the sort of company you’d like to keep, then carry on reading.

Overview

The ClientBilling Coordinator supports the agency’s day-to-day client billing across agency fees and out-of-pocket costs, including media and production. This role prepares invoices, submits approved billing, maintains supporting documentation and follows up on invoice status to help ensure accurate, timely billing and collection.

The position is designed for a detail-oriented finance professional who can manage recurring billing deadlines, maintain organized records and work collaboratively with internal teams and client accounts payable contacts. The Coordinator follows approved billing schedules and established review processes, escalating discrepancies and matters requiring approval to the Senior Manager, ClientFinance.

This role reports directly to Senior Manager, Client Finance, and works closely with Accounting, Media Finance and Account teams.

This position is based in New York City and follows a hybrid work model, requiring three days in the office (Tuesday–Thursday).

Key Responsibilities

Billing Schedules and Purchase Order Controls

· Maintain billing calendars and trackers covering upcoming invoices, contractual deadlines, approval status and outstanding actions; track executed statements of work, approved amendments and applicable purchase orders against planned billing

· Monitor purchase order balances and expiration dates, flag missing, insufficient or mismatched purchase orders, and coordinate with Account, Accounting and Media Finance teams to obtain required billing inputs and resolve routine questions before deadlines are missed

· Maintain current billing checklists and organized client billing instructions, portal procedures, purchase orders, approvals and supporting records

Invoice Preparation and Submission

· Prepare client invoices in our ERP for agency fees, media, production and other approved out-of-pocket costs in accordance with contractual billing schedules

· Validate project codes, invoice descriptions, amounts, purchase order references, payment terms and required supporting documentation; route draft invoices for review and approval before submission

· Submit approved invoices through client portals or designated email channels, retain submission records and confirm acceptance where available

· Resolve routine submission issues with client accounts payable contacts and internal teams; prepare approved invoice corrections and credit documentation with a clear audit trail, including project closeout billing and credit processing under Finance supervision

Invoice Tracking and Accounts Receivable Support

· Track submitted, accepted, rejected and outstanding invoices, including portal status and rejection reasons; follow upon invoice receipt, processing status and expected payment dates under theSenior Manager’s direction

· Coordinate with Accounting to verify recorded receipts and open balances before client follow-up; document payment commitments, disputed items and follow-up activity

· Escalate overdue balances, unresolved issues, billing discrepancies and missing documentation to Finance leadership promptly to support timely billing and collection

Reconciliation Reporting and Process Improvement

· Reconcile billing trackers to ERP invoice records and approved schedules, identifying missing, duplicate or incorrectly coded billing

· Prepare summaries of completed billing, scheduled but unbilled amounts and open billing issues; provide invoice copies, supporting schedules and explanations of billing differences for month-end close and client reconciliations

· Identify recurring billing problems and recommend practical improvements to reduce errors, delays and manual rework

Qualifications

· 1–3 years of experience in client billing, accounts receivable or a comparable finance support role; advertising agency or professional services experience preferred

· Experience preparing invoices, managing purchase order requirements and following contractual billing schedules, with familiarity using Workamajig or a comparable project accounting system

· Working proficiency in Excel, including lookups, filters, basic formulas and billing data reconciliation

· Strong organizational skills and attention to detail, with the ability to manage multiple client accounts and recurring deadlines

· Clear verbal and written communication skills and a collaborative, solution-oriented approach to resolving billing questions with internal teams and client contacts