Welcome to One Underwriting

One Underwriting acts as a Managing General Agent (MGA), that's an authorized agent, for insurers, as part of Aon Nederland (part of Aon plc), for non-life, income and health insurance. In the Netherlands One Underwriting is given the authority by a large number of insurers to accept insurance and handle claims and is thus a quick link between consultancy and brokerage companies and insurers. Managing General Agents (MGAs) represent a significant part of Aon's business both in EMEA and globally. Several of these MGA's operate under the One Underwriting brand.

The UK branch is open specific for clients in an EU/EEA territory

The UK Branch of One Underwriting is established in London in 2019 to facilitate the Aon network offices to maximize opportunities as a single route to the market on specific MGA facilities for clients domiciled in an EU/EEA territory.

We focus primarily on commercial insurance or re-insurance products across Accident and Health, Property and Casualty, Terrorism, Energy, Financial Lines, Marine and Intellectual property. Therefore, One Underwriting - UK Branch received delegated authority from several insurance partners in the UK (company markets and Lloyd's) to provide underwriting and/or claims handling services.

One Underwriting B.V. (UK Branch) will operate as a branch of One Underwriting B.V. in the Netherlands. Throughout the development period we consulted regularly with the Financial Conduct Authority and the Dutch regulator, the Authority for the Financial Markets (AFM), we have obtained the required authorisations and permissions for the One Underwriting B.V. (UK Branch). This model is in line with the guidance issued by the European Insurance and Occupational Pensions Authority (EIOPA) on February 19, 2019 to EU regulators.

How will the UK Branch operate?


To simplify matters for clients who are domiciled in an EU/EEA territory, the UK Branch will handle the entire placement. This means that:

  • One Underwriting B.V. (UK Branch) will manage all exposures inside the EU/EEA and outside the EU/EEA for all clients domiciled in the EU/EEA.
  • Aon Underwriting Management will manage all exposures inside the EU/EEA and outside the EU/EEA for all clients domiciled outside the EU/EEA.


One Underwriting - UK Branch manages claims under the following facilities:

  • Aon Protect personal accident and travel, Download a claim form and return to aum.claims@aon.co.uk.
  • Other facilities are handled via your local Aon broker.


If you have a complaint, please contact us via the following complaint form.

Insurance Product Information Documents (IPIDs)

Contact details

One Underwriting BV - UK Branch

One Underwriting - UK Branch is registered with the Financial Conduct Authority ('FCA') under the Financial Services Register number 542181.

One Underwriting - UK Branch is registered in the UK under UK establishment number BR021307.

One Underwriting (UK Branch)
The Aon Centre, The Leadenhall Building
122 Leadenhall Street
London EC3V 4AN
+44 (0) 20 7623 5500

For more information, please contact your regular Aon contact, or email Andrew Barnes, Head of One Underwriting B.V (UK Branch).

One Underwriting BV

One Underwriting is registered with the Autoriteit Financiële Markt ('AFM') under the register number 12009128.

One Underwriting is registered at the Chamber of Commerce, number 33109041.

One Underwriting B.V.
Condensatorweg 54
+31 (0) 20 430 5240