The government's decision to opt out of the EU-wide financial transactions tax - also referred to as the Robin Hood Tax - will cost the nation's households £21 billion.
This is according to the Trades Union Congress (TUC), which specified this amount of revenue generated by new taxes for high-paid workers in the City of London will now go straight to governments in the European Union.
General secretary of the TUC Brendan Barber explained this could have been used to address national issues such as poverty, paying off the deficit and investing in sustainability.
He claimed that this "wrecks the government's claim that blocking a Robin Hood Tax, despite the idea's popularity with voters, is in Britain's interests", adding the decision was made "just to help the City avoid paying their fair share of tax".
Mr Barber recently called on the coalition to scrap corporation tax relief, claiming this could also boost the economy and sustain growth.