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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Mandatory Payrolling of Benefits from April 2027 - What Employers Need to Know
22nd October 2026
From 6 April 2027, certain taxable benefits in kind will need to be reported through payroll in real time rather than being reported annually on Form P11D.
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Buying (or selling) a US business? Don't let tax be the deal-breaker you didn't see coming
22nd October 2026
US tax due diligence helps buyers and sellers identify, quantify and manage tax risks during acquisitions. Understanding complex federal, state and local tax rules, historic liabilities and business structures enables informed decisions, protects deal value and ensures tax findings shape transaction planning from the outset.
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Non-UK Resident Directors: The Employment Tax Risks Businesses Often Overlook
8th October 2026
Non-UK resident directors can create unexpected UK employment tax and National Insurance liabilities. PAYE withholding, reporting obligations, social security rules and the treatment of expenses can all affect a company’s compliance position, even where directors live and pay tax overseas.
Ready to turn complexity into clarity?
We’re here to help you make informed decisions, with confidence.