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
Helping you navigate the complex rules that apply to US connected people.
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Delinquent US Filers
Helping you seamlessly navigate your route to compliance whilst mitigating risk.
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UK Business Tax Advisory
Practical, commercial, and cross-border insight for entrepreneurs, investors and growing companies.
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Partnership & Fund Reporting
Corporate and partnership tax returns and bespoke structuring support to help you attract global investment.
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Employer Solutions
Providing support and solutions to help employers stay compliant, maximise tax efficiency, and reduce costs.
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Global Mobility Services
Taking the complexity out of moving employees and directors to and from the UK.
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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Cross-Border Structures in the Spotlight: What Budget 2026 Changes for the Internationally Mobile
2nd November 2026
For many internationally mobile individuals, investments held through US LLCs and similar structures can create an unexpected problem: the same income may be taxed differently in different countries, sometimes leading to double taxation.
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Autumn Budget 2026: What the latest trust and pension changes mean for you
2nd November 2026
Following a period of significant change to the taxation of trusts and pensions, Autumn Budget 2026 focuses more on refining and clarifying measures already announced rather than introducing major new reforms.
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Budget 2026: The devil is in the detail – what it means for your business
30th October 2026
The Budget introduces incentives to support UK business growth and investment, but reduces Business Asset Disposal Relief from £1 million to £500,000 from April 2027, potentially increasing CGT for business owners selling their shares.
Ready to turn complexity into clarity?
We’re here to help you make informed decisions, with confidence.