Thanks in part to UK Uncut, the use of tax havens by major corporations is increasingly in the news. Now, an interactive map based on new research from ActionAid lets you see the extent to which these havens are employed by Britain’s biggest companies. As you'll see when you use it below, 98 of the FTSE 100 have a grand total of 8,492 subsidiary companies located in havens around the world. That’s almost 40% of all their overseas operations.

High street banks are the heaviest users with 1,649 tax haven companies shared between Barclays, HSBC, RBS and Lloyds.  Barclays has 174 companies registered in the Cayman Islands alone.  Many of the banks also have significant operations in the developing world.

It’s well known that multinational companies use tax havens to dodge their bills. We think Britain’s biggest companies have serious questions to answer about precisely why they need so many companies in tax havens.

Over the last few years we at ActionAid have been campaigning for companies to become much more transparent about their taxes around the world. Greater transparency would give developing countries a vital tool in the fight against tax dodging, act as a powerful deterrent to companies, and also help expose the scale of the issue.

To help this along, we’ve published all the data on every FTSE100 company as part of our Tax Haven Tracker map. Have a look at which tax havens your local banks, petrol stations and high street shops are using:

We’ve also published all the raw data we uncovered and we’d love to hear from you if you can help make it come alive.