Fee income at the Republic's main accountancy firms increased by 21.5 per cent over the past year with PricewaterhouseCoopers emerging as the highest earner, according to a survey by Finance magazine.

The total fee income at the 22 firms taking part in the annual survey was €782 million, up from €643.4 million last year.

The growth was fuelled by increasing regulation, according to Finance, with international compliance and regulatory changes offering opportunity to the industry.

Among the Big Four accountancy firms, fee income grew 18.4 per cent. PricewaterhouseCoopers overtook last year's highest earner, KPMG, to take the top slot with income of €181 million, a rise of 20 per cent. KPMG increased its fee income by almost 11 per cent to €176 million.

Deloitte had the best year of the Big Four, with fee income growing 30 per cent to €113.5 million. This was broken down into €40 million from audit and accounting, €29 per cent from tax and €23 million from consulting.

With staff members only growing by 4 per cent, Deloitte was found to be the most "efficient" firm, recording the highest fee income per staff member. Its 767 staff members each generated an average of €147,458.

Deloitte's strong year saw it overtake Ernst & Young to become the third-largest accountancy firm in the Republic. Ernst & Young's fee income grew just over 18 per cent to €110 million.

The firms surveyed employ a total of 6,349 people, 414 of them partners.