I switched from a large provider of expat US tax advice to Seán several years ago after being dissatisfied with the level of service I was receiving. I am very glad I made the change. Seán is very knowledgeable about all filing requirements that apply to expat US citizens , and I feel that my situation is reviewed more carefully than ever before. For example, I have not had to correct information in my draft returns, as had been the case before. I also feel that, for the first time, my specific needs are being considered and that I am given advice relevant to that (as opposed to some standard answer that may not always be relevant). Equally importantly, the process is less time-consuming on my part, as Seán is able to discern what information is truly relevant to my filing. Finally, Seán is always readily available to answer any questions I have. I highly recommend him.

As a former U.S. tax adviser, I thought it didn't make sense for me to pay someone else to prepare my own tax returns. Eventually, frustrated with inadequate tax software and constantly-changing rules, I started looking for help. I wanted someone with international tax expertise and Big 4 experience, who could also guide me on the U.S. tax implications of setting up business activities Belgium. Seán O'Connor has been my trusted U.S. tax adviser since 2020. His deep knowledge of U.S. tax and efficient style make him easy to work with.

I’ve been using Sean’s services for over a decade - initially as a US citizen living in Europe, and later following my move to the US. I have always been impressed by the quality of his work, attention to detail, and ability to provide guidance on complicated questions related to my international status. I would highly recommend working with Sean on your tax returns.

I have been working with Sean for (just over) a year, during which he has provided advice and completed my tax returns. He is clear on what I should expect from him and what he expects from me to be able meet deadlines. I appreciate that he responds promptly to my queries with thorough and easy-to-understand explanations

Sean at Oak advisers was recommended to me in an expat forum that I am a member of, and since then I have recommended his services to several others.  He is extremely knowledgeable in US tax law and can is capable of handling even complex reporting requirements.  His rates are also very reasonable when compared to most other expat tax services.

Mr O'Connor has been in charge of preparing my US tax returns since 2012 and he has always done an outstanding job. His in-depth knowledge of the US tax system and his keen eye for the tax complexities that exist for people like me that work for the European Union institutions is unparalleled. His steady hand has helped me both when I was located in Brussels or currently in New York City, and whether I was filing individually or jointly since I got married.
Mr O'Connor knows how to navigate these complex situations and has always provided me with the best advice. I am greatly appreciative of his professionalism, efficacy and timeliness.

We have relied on Sean for several years. His input has been invaluable in helping us ensure timely and accurate tax reporting. He has proven to be an excellent, highly professional alternative for taxpayers who prefer the fully personalized approach of a smaller firm.

This was a our first time filing from overseas and Sean made the process easy. He answered all of our questions and provided expert advice on our unique situation.

At some point, dealing with US taxes as an expat is near impossible without someone who knows what they’re doing – Sean has been a trusted advisor who has helped me navigate this complex world.  My only regret is I wish I would have asked for help sooner!

If you are reading this, it is safe to assume that you know that there are some things on which you should not scrimp…shoes, a good mattress and, of course, your tax advisor. If this is the case, those good shoes will take you places and if you choose to work with Sean, you will sleep better on that quality mattress of yours. Sean sees around corners his clients didn’t know existed, he’s more of a tax coach than an advisor and he’s proactive when helping his clients protect themselves from risk and explore efficient investment opportunities. Take it from this American national married to an EU citizen with complex international advisory needs.

Over our decade of working together, Sean has always been well-organized, responsive and diligent with my tax preparation as an American abroad. The Belgian and US systems are so complex, but Sean knows how to navigate both, so that I can properly present my Belgian & US income to tax authorities from both countries. That binational knowledge saves me a lot of time in researching, explaining and recalculating. I couldn't do it without him!