Senior Manager - International Social Security Tax - London

Our Purpose

At EY, we're committed to building a better working world. As a global leader in assurance, tax, transaction, and advisory services, we leverage our financial products, expertise, and systems to foster a culture of continuous improvement. Through our training, opportunities, and creative freedom, we empower you to innovate and make an impact across our network of over 300,000 professionals and one million alumni. At EY, you lead, inspire, and bring our purpose to life—during your tenure and beyond.

The opportunity

We are seeking an experienced Senior Manager to join our London International Social Security (ISS) Centre of Excellence (COE) team.

We’re looking for someone with strong technical expertise in EU legislation, bilateral social security agreements, and domestic social security/tax legislation, combined with change management skills to deliver high-impact communication and engagement strategies.

Client-facing experience in one or more of the following areas is essential:

• International Social Security (ISS)
• National Insurance Contributions (NIC)
• Assignment Management
• Expatriate Tax

The Team

EY’s ISS practice is the leading global provider of social security services. The London-based team includes ex-social security administration staff, qualified accountants, and tax advisors with backgrounds in expatriate tax, immigration, and assignment management. The team supports a wide range of global advisory and compliance work involving individuals relocating to and from the UK, as well as between other country combinations around the world.

What You’ll Do

Client Delivery & Advisory

• Lead the delivery of global ISS compliance services, including Certificates of Coverage, Modified National Insurance returns, and voluntary contributions.
• Provide expert technical advice on complex international social security issues, such as totalization agreements and multi-country assignments.
• Act as the primary point of contact for clients, building long-term relationships and ensuring high levels of satisfaction.
• Liaise with government authorities in the UK and abroad to resolve client matters.

Strategic Leadership

• Contribute to the development and oversee the rollout of EY’s ISS strategy and service offerings across markets, people, and operations.
• Identify and pursue cross-selling opportunities within PAS and the broader EY service lines.
• Support the creation of thought leadership materials, including articles, presentations, and whitepapers on technical topics and broader trends such as technology.

Team Management

• Mentor and coach junior team members, fostering both technical and professional growth.
• Coordinate efforts across EY’s global network and GDS back-office teams.
• Ensure operational excellence and financial discipline across engagements.

Risk & Compliance

• Oversee risk management and ensure compliance with EY’s policies and regulatory standards.
• Monitor legislative changes and proactively advise clients on potential impacts.

About You
You’ll have:

• Extensive experience in international social security, ideally within a Big 4 firm or equivalent.
• Strong technical knowledge of UK and global social security systems.
• A proven track record of winning and managing complex projects and client relationships.
• Excellent communication, leadership, and organisational skills.
• The ability to work both independently and collaboratively in a fast-paced environment, with a strong commitment to personal growth and continuous learning.

Rewards

We offer a competitive remuneration package where you’ll be rewarded for both individual and team performance. Our comprehensive Total Rewards package includes support for flexible working and career development. Through Flex EY, you can choose benefits that suit your needs—covering holidays, health and well-being, insurance, savings, and a wide range of discounts, offers, and promotions.

In addition, we offer:

• Support and coaching from some of the most engaging colleagues around
• Opportunities to develop new skills and progress your career
• The freedom and flexibility to manage your role in a way that works best for you

EY is an inclusive employer and supports flexible working arrangements to help maintain a healthy work-life balance. We embrace diversity and celebrate you for being you.

Ready to make an impact? We’re eager to hear from you.