Deloitte powered ahead in 2016 as its global fee income grew by 5 percent to US $ 36.8 billion (£ 29.52 billion), nudging it ahead of Big Four rival PwC. 
Last year PwC seized back the top spot after two years of playing catch-up but in 2016 it recorded only 2 percent growth in fee income for a total of £ 28.79 billion, according to the latest global network rankings from International Accounting Bulletin. 
EY remained solidly in third place but still a long way from the top two with income of £ 21.35 billion (3 percent growth year-on-year) and stayed slightly ahead of KPMG, which recorded growth of 4 percent to £ 20.39 billion. 
The Big Four’s dominance shows no sign of letting up as the gap has widened. In fifth spot, BDO saw its fee income grow by 4 percent to £ 6.1 billion while in sixth place RSM enjoyed growth of 5 percent to £ 3.9 billion. Grant Thornton improved its fee income by 3 percent to £ 3.83 billion. 
Overall it was a strong year for the profession globally as every firm in the top 10 recorded growth. 
Outside the top 10, Mazars had a good year as it recorded growth of 6 percent to £ 1.51 billion. The most dramatic increase was from SFAI, 17th place, which saw its income rocket by 142 percent to £ 391 million. On the other end of the spectrum, MGI Worldwide, 18th, suffered a fall of 20 percent to £ 351.1 million. 
The big firms continue to increase their workforce – with the Big Four employing almost one million people globally combined. 
Despite outperforming EY in terms of income this year, PwC continues to employ significantly fewer people. EY increased its workforce by 9 percent to a total of 230,800, PwC increased its number by 7 percent to 223,468. 
Deloitte is the number one employer with a total of 244,400 people working for the firm, while KPMG is fourth largest with 188,983. BDO increased its global workforce by 5 percent to 67,731 while Grant Thornton boosted its numbers by 11 percent to 47,004.