Germany is Amazon's biggest market outside North America, its annual report shows, but until recently all sales and almost all profits were reported via lightly taxed Luxembourg companies.

Amazon's main German operating unit, Amazon.de GmbH, manages the German website and oversees deliveries but is funded by payments from the Luxembourg companies.

Accounts filed in late April and only publicly available in recent weeks, show Amazon.de made a profit of just 32 million euros in 2014 and paid corporate income tax of 11.9 million euros. Using the average exchange rate for 2014, that equates to around $16 million in tax.

"Corporate tax is based on profits, not revenues. E-commerce is a low-margin business and highly competitive, and Amazon continues to invest heavily around the world, which means our profits are low," an Amazon.de spokesman said.

The company said last week it had introduced changes in the United Kingdom, Germany, Spain and Italy from May 1, so that future sales would be booked in these countries.

Tax experts said the new arrangement could require Amazon to pay more tax in future years.