Facebook will stop routing advertising sales of its largest United Kingdom clients through Ireland, increasing its British tax bill by millions of pounds in a bid to improve transparency after facing criticism on tax avoidance.

Changes will be made in April, with the higher tax bill to be paid next year. Smaller business sales, where advertising is booked online with no staff intervention, will still be routed through the company’s Ireland offices, which will remain the firm’s international headquarters.

On Monday Facebook will inform its larger U.K. customers that from April they will receive invoices from Facebook U.K. and not Facebook Ireland, a spokesman for the company told Bloomberg in an emailed statement. It means British sales made directly by the firm’s U.K. team will be booked in the United Kingdom, not Ireland. Facebook U.K. will then record the revenue from these sales.

Facebook received widespread criticism in October after the social network giant was revealed to have paid only 4,327 pounds ($6,128) in taxes for 2014, less than the average U.K. worker. Google has also faced controversy over its U.K. tax affairs, settling a 130 million-pound payment in back taxes in January.

The overhaul of tax structure comes after increasing global pressure on its tax affairs and as a reaction to changing tax rules, the BBC, which first reported the news said, citing unidentified sources. Last year the U.K. implemented a new Diverted Profits Tax that assesses a 25 percent rate on the profits of companies found to have avoided U.K. tax by using “contrived” arrangements. The current top U.K. corporate tax rate is 20 percent, and it is set to fall to 18 percent by 2020.

Facebook does not break out how much revenue it earns from U.K. sales or what portion of those sales are supported by U.K.-based sales representatives rather than booked online without human support. The company employs 850 people in the U.K. and Facebook spokesman Chris Norton said sales booked by local sales people represented “a substantial” portion of its total sales to U.K. customers.

The changes to Facebook’s tax structure apply only to the amount it will pay going forward and does not address past concerns. In its latest U.K. financial filings, Facebook revealed unspecified contingent tax liabilities for the years 2010 through 2014. The company said that it planned to defend any claims for back taxes and that it did not believe it “probable” that it would have to pay any back tax.