According to EU documents posted on UK news website The Financial Times, Sweden's large rebate follows new calculations by the European Union, which take into account "adjustments" to countries' anticipated finances.
Sweden's TT news agency reports that the EU has been trying a new way to calculate countries' gross domestic product (GDP), one of the primary indicators used to gauge the growth of a nation's economy. It previously predicted that this could lead to inaccurate predictions of contributions by different member states.
The UK, by contrast, is being asked to pay back €2.1 billion (19.3 billion kronor, $2.65 billion), as a result of its economy performing better than expected.
The Netherlands, Italy and Greece could also have to pay money back, with France and Germany due significant refunds.
"The Commission services are aware that in some cases this might have a significant budgetary impact in terms of cash-flow," reads the leaked document, which adds that the figures are "provisional estimates".
A senior British source working within the UK's Cabinet Office told the Financial Times:
"It is not acceptable to just change the fees for previous years and recover funds on a moment's notice. The EU Commission has not been expecting this money and does not need this money, and we will work together with other countries facing a similar way to change this".