Facebook paid only £28.5m in tax in Britain last year, according to freshly released accounts that have baffled experts and drawn fire from a prominent tax campaigner.

In a filing with Companies House, the firm’s UK arm reported gross sales, mainly to advertisers, of £1.6bn for 2018. Of that, only half is what it called “recognised revenue”. With various expenses taken out, Facebook’s taxable profit amounts to £96.6m.

Two tax lawyers who spoke to The Independent on condition of anonymity said they could not fully understand the accounts.

But even an accounting expert, best-placed to make sense of the document, was mystified, saying it is “opaque”.

Prem Sikka, professor of accounting at Essex Business School, tweeted: “Corporate tax havens: Facebook’s UK operations paid £28m in tax last year despite record £1.6bn in sales. Ultimate controlling entity is in Delaware. Accounts are legally compliant but opaque; intragroup transactions – key to profit shifting – hard to see.”

Facebook birthday: 15 defining moments for the social network Show all 15 1 /15 Facebook birthday: 15 defining moments for the social network Facebook birthday: 15 defining moments for the social network Facebook is born On 4 Feb, 2004, 19-year-old Harvard student Mark Zuckerberg launched a website called 'TheFacebook' from his dorm. Within 24 hours the college social network had more than 1,000 users Wikimedia Commons Facebook birthday: 15 defining moments for the social network Winklevoss twins sue Zuckerberg Within one week of launching, fellow Harvard students Cameron Winklevoss, Tyler Winklevoss and Divya Narendra accused Zuckerberg of stealing their idea. It would be four years later when the resulting lawsuit was finally settled Facebook birthday: 15 defining moments for the social network Open for business The social network finally opened it platform to everyone on 26 September, 2006. The move proved the catalyst in supercharging the site's already explosive growth PA Facebook birthday: 15 defining moments for the social network Billion-dollar bid Yahoo offered $1 billion to buy Facebook in September 2006 but Zuckerberg turned it down. 'I don’t know what I could do with the money,' Zuckerberg reportedly said. 'I’d just start another social networking site' Reuters Facebook birthday: 15 defining moments for the social network In the money In September 2009, almost five years since the site launched, Facebook turned a profit for the first time Getty Images/iStockphoto Facebook birthday: 15 defining moments for the social network Taking the lead Facebook overtook MySpace in 2010 to become the world’s most popular social network Facebook birthday: 15 defining moments for the social network Taking on the tech giants In 2011, Google launched its own social network that it hoped would knock Facebook from its perch. Despite its initial success, Google+ ultimately failed and will be shut down completely in 2019 Getty Facebook birthday: 15 defining moments for the social network Facebook goes public On 18 May, 2012, Facebook went public. The initial public offering raised $16 billion – the third largest in US history Facebook birthday: 15 defining moments for the social network Gobbling up the competition Facebook acquired Instagram in April 2012 for $1 billion, consolidating its position as the world's leading social network Reuters Facebook birthday: 15 defining moments for the social network One billion users On 4 October, 2012, Zuckerberg announced that Facebook had hit 1 billion users. 'If you’re reading this: thank you for giving me and my little team the honour of serving you,' he wrote in a blog post Getty Images Facebook birthday: 15 defining moments for the social network Expanding its empire In February 2014 Facebook acquired the messaging app WhatsApp for $19.3 billion REUTERS/Dado Ruvic Facebook birthday: 15 defining moments for the social network Two billion users In June 2017, Facebook passed the 2 billion user milestone REUTERS/Dado Ruvic Facebook birthday: 15 defining moments for the social network Privacy scandal On 17 March 2018, news broke that UK firm Cambridge Analytica had harvested data from around 87 million Facebook users for the purpose of political profiling in the build up to the 2016 US presidential elections Shutterstock Facebook birthday: 15 defining moments for the social network Record profits Despite the scandals and subsequent #DeleteFacebook campaign, Facebook posted record profits just before its 15th anniversary, the equivalent of $7.37 from each of its 2.32 billions users iStock/Independent Facebook birthday: 15 defining moments for the social network Unhappy users A study found that people are happier when they don’t use Facebook, adding to mounting evidence surrounding the impact social media has on mental health Rex Features

Many multinational companies set up offices in countries with the lowest tax rates and shift their profits there.

Dame Margaret Hodge, a Labour MP who chairs the All-Party Parliamentary Group on Responsible Tax, criticised the amount of UK tax paid by Facebook as too low, following a tax bill of just £7.4m in 2017.

“One year later and little has changed,” she tweeted. “These big corporations simply must pay more tax. They rely on our infrastructure, our expertise and our sales, so they must pay their fair share into society. Still outrageous.”

The challenge of taxing global digital companies, such as Facebook, Amazon and Google, is particularly acute as they do not need to be physically present in a country to sell their services there. Existing international tax rules, dating back to the 1920s, mean companies can be taxed only in countries where they have a physical presence.

On Wednesday, the Organisation for Economic Cooperation and Development published a proposal that would break with that principle by requiring companies to pay tax wherever they have “significant consumer-facing activities” and generate their profits, whether or not they are located there.

Arun Birla, tax partner at law firm Paul Hastings, welcomed the proposal, noting the current global push “for equitable international taxation rights and combatting aggressive tax avoidance through profit shifting”.