Complexity to clarity, wherever you are in the world
At Ostberg Sinclair & Co. we believe that great tax advice is only as valuable as the way it’s delivered.
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US private clients
Get help navigating complex compliance and planning opportunities in the US, UK and internationally.
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UK private clients
Effective advice and strategic tax management, ensuring you’re being as economical as possible while meeting compliance obligations.
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US corporate & international tax
Make sure you’re compliant with tax regulations, and get support for connected individuals, without ambiguity.
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Trusts, Estates, & Family Services
Get help with estate, inheritance, and divorce planning, and ensure tax compliance in line with your fiduciary obligations.
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US connected business owners & entrepreneurs
Navigate complex requirements and planning associated with international business activity.
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Delinquent US filers
Navigate complex requirements and planning associated with international business activity.
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UK business tax advisory
Navigate tax and financial planning across fundraising, expansion, business exits, and long-term structuring.
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Partnership and fund reporting
Navigate tax and financial planning across fundraising, expansion, business exits, and long-term structuring.
DR DRE“The only two things that scare me are God and the IRS”
Why Ostberg Sinclair & Co?
Ostberg Sinclair & Co., was founded with a clear purpose: to put people first. After years of leading successful teams at Big Four and top-tier firms, our leadership saw an opportunity to create something different—a boutique advisory practice built around relationships, not rigid processes.
From the outset, we’ve challenged convention. We believe clients deserve not only technical excellence but empathy, clarity, understanding that culminates in advice tailored to their unique circumstances. That’s why we’ve built a conflict-free environment where complex tax, succession, and structuring issues are handled with care.
Latest knowledge
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“My AI told me so” — Why that won’t save you with the IRS
20th March 2026
As artificial intelligence tools become fixtures in how people research and manage their finances, a question is quietly moving from hypothetical to urgent...
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When tax systems collide: Why the UK is rethinking LLCs
21st April 2026
When Rachel Reeves announced that the government will consult on the UK tax treatment of US LLCs, it may not have grabbed headlines...
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Tax Situationships: When Two Become One (Whether They Like It or Not)
10th February 2026
In the lexicon of modern romance, a "situationship" describes a relationship that refuses definition - two people who drift together, share experiences (and...
Ready to turn complexity into clarity?
We’re here to help you make informed decisions, with confidence.