The broker says it has also generated savings of $10m as a result of operational improvement program
Willis spent $31m in the first quarter of 2015 as a result of the restructuring costs relating to its Operational Improvement Program.
The brokers generated savings of $10m as a result of the program.
Total restructuring costs from the program were $31 million in the first quarter of 2015.
Ten million dollars relate to costs as a result of the reduction in staff, while $21m relates to professional services and other costs.
Broken down by divisions, $4m came from Willis GB arm, $6m from the capital, wholesale and reinsurance division, $7m from North America, $3m from the international arm, and $11m from the corporate division.
The programme includes the relocation of 3,500 support roles, a reduction in the number of support staff, lease consolidations and a simplification of the IT systems.
The broker is planning to make savings of $420m by 2017 as a result of the program.
Willis said it would provide an update on the progress of the program and associated spend and savings estimates when it reports its second quarter 2015 results.