US & UK Accountants For IRS 1040 Taxes & HMRC Self-Assessment Tax Return Services

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Are You an Expat Living in the UK or the US? Confused About Filing Tax Returns? Look No Further!

Navigating the maze of tax laws and regulations can be a headache, especially when you’re an expat living miles from home. Whether you’re an American in the UK or a Brit in the US, we’re here to make your tax season a breeze. Welcome to Optimise Accountants, your one-stop solution for filing tax returns with the IRS and HMRC. Our services will help you stay compliant whilst reducing taxes.

Why Choose Us?

Expertise Across Borders: Our team is well-versed in US and UK tax laws. With rich experience handling complex international tax situations, we’re perfectly equipped to guide you through the nuances of filing in both countries.

Streamlined Process: Our state-of-the-art software integrates with both IRS and HMRC systems, ensuring a seamless process. Say goodbye to endless forms and hello to a user-friendly interface.

Personalized Service: Taxes aren’t one-size-fits-all. Our advisors will work closely with you to understand your unique situation and deliver tailored solutions. We take the time to get to know you because a personalized approach is best.

US & UK Tax Return Services We Offer:

Expatriate Tax Returns: Are you an American living in the UK or vice versa? We specialize in US Form 1040 and UK Self Assessment Tax Returns, taking into account your expat status for optimal tax treatment.

Foreign Asset Reporting: Navigating Form 8938, Form 3520, or FBAR? We’ll help you comply with all your foreign asset reporting requirements hassle-free.

Tax Planning: Minimize your tax liability through our sophisticated tax planning strategies, including using tax credits and deductions available to expats.

Business Tax Compliance: Running a business abroad? We also handle corporate taxes, including VAT and sales tax concerns in the US and the UK.

US & UK Tax Return Key Deadline Dates to Remember:

Keeping track of tax return deadlines for both the US and the UK is critical for avoiding late penalties and ensuring full compliance with tax laws. In the United States, the deadline for individual income tax returns, usually filed using Form 1040, is 15th April.

If you have foreign bank accounts, the Foreign Bank Account Report (FBAR) is also due on 15th April, but it comes with an automatic extension to 15th October 15th if needed. Businesses often have deadlines depending on their structure, like 15th March for S-Corps and partnerships.

On the UK side, the tax year ends on 5th April. If you’re filing a Self-Assessment tax return online, the deadline is 31st January of the following year. Paper returns are due by 31st October of the year the tax year ends. For corporations, the Corporation Tax Return (Form CT600) is generally due 12 months after the accounting period it covers.

By being aware of these key dates, you can plan, manage your financial obligations more effectively, and avoid the stress and financial burden of late fees or penalties.

Tax return extension

The US and the UK offer some deadline extensions for filing tax returns, but the rules vary. In the US, you can get an automatic six-month extension by filing Form 4868, but this only extends the filing deadline, not the payment deadline.

HMRC doesn’t offer extensions for Self-Assessment tax returns in the UK, but exceptions may be made for “reasonable excuses” like illness or technical issues. Both tax agencies sometimes offer extensions for exceptional circumstances, such as natural disasters or pandemics. It’s crucial to consult with a tax professional if you think you’ll need an extension to ensure you meet all requirements and avoid penalties.

Tax Return Amendments

Amending tax returns in both the United States and the United Kingdom is a process that allows you to correct errors, update information, or claim overlooked benefits after your original tax return has been filed. In the US, the typical form used to amend a federal income tax return is Form 1040X. You generally have three years from the date you filed your original return or two years from the date you paid the tax, whichever is later, to file an amended return. The IRS typically takes 8-12 weeks to process an amended return.

Amending a UK tax return differs slightly based on how you filed. If you used online Self-Assessment, you can log in to your HMRC account and make changes directly. For paper returns, you’ll need to download a new tax return, complete it, and mail it to HMRC with the sections you’ve updated marked. The deadline for making amendments to your UK Self-Assessment tax return is one year from the original submission deadline (January 31st for online returns).

Understanding how to amend tax returns correctly is crucial, as errors can result in penalties or trigger audits. Both the IRS and HMRC provide comprehensive tax amendment guidelines, and given the complexity, many seek professional help to ensure that the amendments are accurate and compliant with current tax laws.

Meet Our Stellar Team: UK ACCA and U.S. EA Certified

One of the strongest selling points of Optimise Accountants is our unparalleled team of experts. Not only are we skilled in the art of taxes, but we’re also uniquely qualified on both sides of the Atlantic.

Why is this important for you?

When you’re dealing with tax laws in two different countries, one certified accountant just won’t cut it. That’s why our team consists of accountants who are not only members of the Association of Chartered Certified Accountants (ACCA) in the UK but are also Enrolled Agents (EA) in the U.S.

ACCA Certified for the UK Market:

Our ACCA certification ensures that you’re getting the best and most accurate advice on UK tax laws. ACCA is globally recognized and offers a strong focus on professional values, ethics, and governance. These are essential traits as we deal with the complex UK tax system.

EA Certified for the U.S. Market:

Being an Enrolled Agent is the highest credential the IRS awards. This allows us to represent taxpayers before the IRS for audits, collections, and appeals. Our EA-certified professionals know U.S. tax laws like the back of their hands, making us more than qualified to help you navigate even the trickiest U.S. tax situations.

Double the Expertise, Double the Peace of Mind:

Our dual certification means we’re proficient in U.S. and UK tax environments. You won’t need to hire multiple specialists; we’ve got all your needs covered under one roof. Whether you’re facing issues with the IRS or HMRC, our team can effectively represent and advise you, maximizing your financial benefits and minimizing stress.

By choosing us, you’re opting for a skilled, ethical, and supremely qualified team. Trust us to provide you with top-notch, cross-border tax solutions that are second to none.


A dynamic team of tax experts at Optimise Accountants who are dual-certified as ACCA Chartered Certified Accountants in the UK and Enrolled Agents in the U.S., standing in a modern office setting. The team is dedicated to providing comprehensive, cross-border tax solutions for expats living in the United States and United Kingdom. Whether dealing with IRS or HMRC issues, our professionals offer a unique blend of qualifications to navigate complex tax laws effectively, ensuring stress-free tax filing and optimized financial benefits. Trust us for all your tax needs for tax filing to the Internal Revenue Service (IRS) and HMRC (UK)

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US & UK tax return filing and amendment services by international expat accountants. We will help British and Americans file original and amendments within the deadlines. We can also help you obtain FBAR & 1040 tax return extensions with the IRS. We are EA and ACCA qualified accountants


What types of U.S. tax returns do you specialize in?

We specialize in a variety of U.S. tax returns including individual Form 1040, corporate returns via Form 1120, as well as partnership and LLC filings through Form 1065. Our expertise extends to foreign income reporting, small business taxes, and specialized forms like Form 8938 and FBAR for those with foreign financial assets.

How do you make the U.S. tax return process easier for your clients?

We employ state-of-the-art software that integrates with the IRS e-filing system, providing a smooth and secure filing experience. Additionally, our Enrolled Agents (EAs) offer personalized tax planning and advisory services to minimize your tax liability and optimize your financial situation. We streamline the documentation process, making it easier for you to upload and verify your tax-related documents online.

Can you assist with IRS audits or disputes?

Absolutely. As Enrolled Agents, we're licensed to represent taxpayers before the IRS. If you find yourself facing an audit or have disputes concerning back taxes, penalties, or other compliance issues, we can guide you through the process. Our goal is to resolve any issues as efficiently as possible while safeguarding your rights and financial interests.

What types of UK tax returns do you handle?

We handle a wide array of UK tax returns, including but not limited to the Self Assessment Tax Return (SA100), Corporation Tax Return (CT600), and Partnership Tax Return (SA800). Our expertise also extends to more specialized areas, such as non-residency tax issues, capital gains tax, and inheritance tax.

What makes your UK tax return service stand out?

Our service stands out due to our ACCA-certified accountants who are well-versed in UK tax law. We take a personalised approach to understand your unique tax situation. Additionally, our advanced software seamlessly integrates with HMRC's systems, offering you a hassle-free and secure way to file your UK tax returns online.

Can you assist with HMRC investigations or tax disputes in the UK?

Absolutely, our ACCA certification enables us to represent you professionally in any dealings with HMRC. If you're facing a tax investigation or dispute, we'll guide you every step of the way. Our aim is to resolve any issues swiftly, while minimizing your liability and stress.

Absolutely, our ACCA certification enables us to represent you professionally in any dealings with HMRC. If you're facing a tax investigation or dispute, we'll guide you every step of the way. Our aim is to resolve any issues swiftly, while minimizing your liability and stress.

Book a call to see how we can help you.


Consultation options.

We offer the two following options for initial consultations.


Our Ongoing Accountancy Services

We charge on a fixed monthly fee

  • - Accounts submitted to HMRC & Companies House

  • - Tax support when needed (no extra charge)

  • - An holistic review of your tax structure and future plans

  • - Annual tax return review to discuss future tax plans


Tax Call + Report + Video Recording

Want tax advice right now? Book today

  • - Upload your questions in advance

  • - A qualified tax advisors discuss the very best solution with you

  • - A tax report & meeting recording is sent within 48 hours

  • - Clarification questions are answered via email

Booking your appointment.