From the accountant's perspective, the rule of thumb is the less cost the better in judging just about anything that falls under his gaze.

So it is hardly surprising to find that the profession's A Plus Magazine, the official journal of the Hong Kong Institute of Certified Public Accountants (HKICPA), favours greater integration of disparate systems in the Pearl River Delta, from Hong Kong to Guangzhou, which to their minds will create a global economic powerhouse, only surpassed by the United States and Germany.

With a bridge linking Hong Kong to Zhuhai and Macau being built, high-speed rail putting Guangzhou 48 minutes away from Hong Kong, it seems Guangdong and Hong Kong are on an inexorable path towards integration.

The conurbation has been given many names in past decades - Pearl River Delta, Zhujiang Delta, Yuegang'ao Greater Bay Area - but China's powerful National Development and Reform Commission has settled on the term Guangdong Hong Kong-Macau Greater Bay Area (GBA) in the 13th Five-Year Plan.

The area covers 40,000 square kilometres and contains 120 million people, making it the world's third-largest trading economy, according to Bank of America Merrill Lynch.

Earlier estimates put the construction cost of the Hong Kong-Zhuhai-Macau Bridge at CNY110 billion (US$15.9 billion). But now the project has run over budget by CNY10 billion.

"The Greater Bay Area is a prime candidate for city cluster development because it already has good integration across the region with concentrations of economically robust industries," said Bank of America Merrill Lynch analyst Angello Chan.

Said New Sports Group chief financial officer Tony Fong: "CPA firms will be offered participation into various projects such as audit and financial due diligence in connection with crossborder acquisitions by listed companies in Hong Kong and multinational corporations."

But Mr Fong touched on just one of the lingering problems affecting such a promising union, that is, the differing standards and procedures on both sides of the border.

"One of the hurdles for CPAs [chartered public accountants] in Hong Kong to practise audit or taxation in China is the lack of mutual recognition of professional qualifications between the two places," said PricewaterhouseCoopers (PwC) partner Jeremy Choi.

BDO Unibank managing director Clement Chan and a past president of the HKICPA, noted the tight restrictions on Hong Kong CPAs practising in the mainland. He said allowing HKICPA members to become partners at Qianhai's accounting firms would attract more Hong Kong firms to the area, he said.

There were other critics and criticisms. Hong Kong Legislative Councillor Christopher Cheung, who represents financial services, chided special economic zones for focusing on majors like HSBC and Tencent and overlooking small- and medium-sized enterprises.

But Witman Hung, principal liaison officer for Hong Kong at the Shenzhen Qianhai Authority, said there had been changes since. Previous capital requirements of HK$5 million have been removed to make it easier for smaller companies. "Many SMEs may not know about the change in the requirements," he said.

Mr Hung has said that allowing Hong Kong CPAs to work in Qianhai without requiring mainland qualifications is an objective, but unlike architecture and engineering, auditing is a centrally supervised profession and reforms are expected to take some time.

Mr Fong was also optimistic, saying there are opportunities despite regulatory curbs. "Individual Institute members could seek more challenging management positions looking after the financial operations of new business entities in relation to investment projects within the GBA," Mr Fong said.

Mr Choi hoped the mainland government would no longer require Hong Kong residents to make contributions to China's social fund as they already contribute to the territory's Mandatory Provident Fund.

Edward Au, in the National Public Offering Group at Deloitte China said the infrastructure developments could change the way Hong Kong and Guangdong business deals with each other.

"With the high-speed train you could go from Hong Kong to Guangzhou in 48 minutes and to Shenzhen in only 20 minutes," Mr Au said.

"The Hong Kong-Zhuhai-Macau Bridge will be a very important connection to mobilise Hong Kong CPAs travelling to Guangzhou. Despite new technology the best approach is face-to-face meetings."

Moreover, said Mr Au, authorities have proposed free fund flows between Hong Kong and GBA cities in Guangdong. "More efficient fund flows would open up business to more collaboration and cooperation. This will lead to more openness among city governments."

Hong Kong can also capitalise on the opportunities arising from the GBA to reinforce and enhance its status as a global financial centre, an offshore yuan hub and an international asset management centre.

Said Mr Choi: "We can continue to enhance the two-way flow of cross-border yuan funds and deepen the mutual financial market access between Hong Kong and the mainland."

Hong Kong, he said, should be positioned as the premier financing platform for new businesses and investment in the GBA region. "This will in turn help to source new markets and diversify the investment products for the financial services industry in Hong Kong."

Said UBS analyst Dennis Lam: "The GBA has the potential to be game-changing on a national level. While special zones tend to serve a single purpose on a small scale, we believe the GBA will develop into a world-class metropolis. Through greater integration and better resource allocation, the GBA could become a major driver of economic growth for China."