Cassell & Co is now Keystone Advisory & Tax. Same team, same trusted advice, new name.

Empowering Small to Medium Businesses with Practical Accounting Solutions.

Keystone Advisory & Tax is a client-focused accounting firm based in Surry Hills, Sydney, delivering personalised support to small to medium businesses and creative professionals. We go beyond tax and compliance—partnering with designers, founders, freelancers, and entrepreneurs to simplify complexity and build confidence in your numbers. Whether you need strategic advice or a reliable second set of eyes, we’re here with clarity, care, and genuine connection. Get in touch with us today!

Get In Touch

Tailored compliance and advisory support, delivered with precision, care, and a deep understanding of your business.

WHAT WE DO

Comprehensive Support for Your Business.

From tax and bookkeeping to business advice and specialised services, we provide the practical support you need.

See our services

Taxation

We provide clear, practical accounting advice to help you meet your tax obligations with ease.

Business Advice & Structuring

From tax planning to business strategy, we provide tailored support to help small to medium businesses and creatives build strong, sustainable foundations.

Bookkeeping

Whether you need full-service bookkeeping or just the tools to manage your own records, our team is here to help.

Specialist Services

We understand the unique financial needs of creative professionals and offer tailored accounting solutions to help your business thrive.

“Kat Abrahams and the team are an absolute pleasure to work with. Kat brings a proactive approach to everything she does, is always available when I need her, and provides the kind of thoughtful support that makes a real difference. I’m grateful to have her as part of my team and would highly recommend her. “

Genevieve Hromas
OKO OLO STUDIO

WHO WE ARE

We’re With You, Every Step of the Way.

Keystone Advisory & Tax is a client-focused accounting firm based in Surry Hills, Sydney. With decades of experience, we specialise in tax, bookkeeping, and business advice tailored for small to medium businesses and the creative industry.

Meet the team

“I love working with Kat and the team at Keystone. They are not just awesome accountants, they provide an honest and objective frame of reference for my business. That’s invaluable when it comes to helping me with the responsibilities of being a business owner – and our chats always make me feel so much better!”

Monica Davidson
Creative Plus Business

CUSTOMER REVIEWS

What Our Clients Say About Us.

We’re proud to support businesses doing great things—and even prouder when they share their positive experiences with us.

Start A Conversation Today.

Ready to take the next step? Get in touch and tell us about your business – we’d love to explore how best we might be able to work together!

Email: hello@keystoneadvisoryandtax.com.au

Phone: +61 2 9716 5120

Head Office: Suite 410, 55 Holt Street, Surry Hills NSW 2010