About Us
Hi, I'm Mary Sandberg, founder of Oak & Willow Billing.
I started Oak & Willow Billing because I saw how often small and independent medical practices were being underserved by billing solutions built for large healthcare systems. I wanted to build something different: a billing partner that treats every practice like it matters, because it does.
Today, Oak & Willow Billing provides full-service medical billing, accounts receivable management, credentialing, and payer contracting support to solo and independent practices across the United States. We handle the administrative complexity of revenue cycle management so providers can spend less time on paperwork and more time with patients.
With years of hands-on experience in claims management, denial resolution, and provider credentialing, I've built a practice-first approach: responsive communication, accurate and timely billing, and a genuine investment in each client's financial health.
Outside of work, I spend my time with my husband and our three boys — camping, exploring, and making memories together. That same sense of partnership and care is what I bring to every client relationship.
My team and I look forward to working with you!
Our Commitment
At Oak & Willow Billing, our commitment is built on integrity, transparency, and personalized service — values that guide every claim we submit, every call we make on your behalf, and every report we send.
We know that behind every claim is a provider working hard to care for patients, and behind every denial or delay is real revenue your practice depends on. That's why we treat your accounts receivable as if they were our own — following up promptly, communicating clearly, and never letting claims sit unnoticed.
We're committed to:
Accuracy — clean claims, correct coding, and careful attention to payer requirements to reduce denials before they happen
Responsiveness — timely follow-up on outstanding claims and quick answers when you have questions
Transparency — clear, regular reporting so you always know where your practice stands financially
Partnership — taking the time to understand your practice's specific needs, specialty, and goals
Our goal is to be a reliable extension of your team — handling the operational and financial details so you can concentrate on what you do best: caring for your patients.