Although sustainability report has existed for a long time, the frequency and amount of information presented has increased significantly in recent years (KPMG, 2011) with many large companies not only present this information in their annual report but also prepare separate sustainability reports. Their concerns have been raised about reliability and completeness and the need to ensure sustainability reports (KPMG, 2011; Simnett, Vanstraelen and Chua, 2009). Despite this growing number of reports are receiving third party assurance (KPMG, 2011; O'Dwyer, 2011) and Big 4 accounting firms are gaining increasing market share (O'Dwyer et al., 2011), little is known about the auditor's judgments on these types of engagements, in particular, material judgments which are important because they evaluate reliability of the reported data. These material judgments also form an important input into the negotiations between the auditor and the client with respect to the consequences related to the financial statements. Materiality has been considered a key concept in both audit theory and practice for decades (Messier et al., 2005). Previous research only addressed traditional financial statement audits (Messier et al., 2005) and did not consider the auditor's material judgments in other assurance engagements. As other assurance engagements become commonplace, it is important for auditors and regulators to understand what impacts the auditor's material judgments regarding these types of engagements. The Big4 audit firms (Deloitte, EY, KPMG and PWC) are the largest international professional firms providing audit, assurance, tax, consulting, advisory, accounting, corporate finance services.
professional and legal. Among them, ensuring sustainability refers to the assurance of sustainability reports (SR). Professional accountants are qualified for this service because of their professional standards and because they are required to follow ethical principles (Peters and Romi, 2014). At the end of the last century, the financial audit market had to overcome important challenges (Elliott, 1997), which gave rise to the development of new markets. The American Institute of Certified Public Accountants (AICPA) has predicted that there are possibilities for auditors to expand their services and that they will face more competition. In this new context, Big4 accounting firms had to assess the opportunities and threats when undertaking other types of assurance. In recent years, both the provision of new services (SR) and the presence of new agents (certification companies and consultants) in the market are assured. SR rates are guaranteed and Big4's weight in this new market is growing over time.
Mock et al (2013) reported that the rate of SR guaranteed by Big4 increased from 35.4% in 2002-2004 to 51.35% in 2006-2007. In addition, KPMG highlights that Big4's market share has increased from 60% of guaranteed SR in 2005 (KPMG, 2008) to 67% of guaranteed SR in 2013 (KPMG, 2013). Most of the previous studies on assurance engagements refer to the Big4 in general and examine the differences between them and other assurance providers (Simnet et al., 2009; Hassan et al., 2009; Hassan et al., 2009; Perego, 2009). Little is known about the specific Big4's role in this market. Fernandez-Feijoo et al (2015) reported the dominant position of Big4 in securing SR with the following allocation: KPMG 18%, PWC 19%, Deloitte 10% and EY, 14%. The lowest percentage of assurance claims made between 2011-2012 by Deloitte and EY can be explained by the fact that both are headquartered in New York and not until recent years , sustainability becomes an important topic in the US.
Through the study of sustainability reports in countries around the world, the current trend of businesses is towards using assurance suppliers - reputable audit committees to enhance the quality of information on published reports. Large assurance providers like Big 4 will satisfy all these needs of businesses by professionalism, security and specialization.
3.2. The reality of publishing sustainability reports at enterprises in Vietnam
Regarding information disclosure, on October 6, 2015, the Ministry of Finance issued Circular No. 155/2015/TT-BTC guiding information disclosure on the stock market, effective from January 1, 2016, replacing Circular No. 52/2012/TT-BTC; towards building a green finance, realizing the National Strategy on green growth for the period 2011 - 2020 and vision to 2050 approved by the Prime Minister in Decision 1393/QD-TTg, Notification Decree 155 stipulates that public companies must disclose information related to sustainable development. Sustainable development content is included in the annual report, or made separately as a separate report. Thus, building sustainable development content is a mandatory requirement for public companies. Surprisingly, in Vietnam, many enterprises and corporations have pioneered in preparing sustainability reports even before there is a mandatory legal requirement such as: Bao Viet Group (BVH), Dairy Joint Stock Company Vietnam (VNM), DHG Pharmaceutical Joint Stock Company (DHG), Century Yarn Joint Stock Company (STK), Novaland Group (NVL), Gia Lai Electricity Joint Stock Company (GEG), Bao Viet Securities (BVS) ), Petrolimex Group (PLX), Saigon Thuong Tin Commercial Joint Stock Bank (STB), FPT Securities Joint Stock Company (FPTS), etc. Some businesses have actively voluntarily applied sustainability reporting frameworks according to the set of standards of the Global Reporting Initiative (GRI). Many pioneering enterprises have conducted detailed assessments of the degree of sustainable integration into their strategies and operations. FPT Securities Joint Stock Company has very well integrated the report contents according to the GRI Standards and 17 sustainable goals of the United Nations into its operations and reports. The company's sustainability report over the years is highly appreciated in both content and form. The report clearly demonstrates the governance processes, including assessment of material issues, risks, feedback and stakeholder
expectations, linking this assessment to the development of specific plans and targets to ensure sustainable growth.
Figure 1: GRI Standards compliance table at FPT Securities Corporation (FPTS)
(Source: FPT's annual report, 2019)
Meanwhile, the sustainability report of Vietnam Dairy Products Joint Stock Company - Vinamilk (VNM) is prepared according to GRI Standard with a clear structure, concise presentation, combined with the use of drawings, properly illustrated and graphed. VNM's
report has conveyed specific strategies and actions, showing the connection with the global sustainability context in general and Vietnam's dairy industry in particular.
Figure 2: GRI Standards compliance table at Vietnam Dairy Products Joint Stock Company (VNM)
(Source: Vinamilk 's annual report, 2020) Making independent sustainability reports certified by third parties is a trend of businesses around the world. By 2011, there were more than 1,200 enterprises with independently audited sustainability reports. In Vietnam, Vinamilk pioneered in auditing sustainability reports because of the significant benefits this report brings. First of all, an audited sustainability report will help increase the level of reliability, transparency and professionalism in operations, helping businesses improve their reputation in the eyes of domestic and international investors. This will help improve the transparency of non-financial information, providing investors and interested parties with a comprehensive and strategic view of the entire operation of the business. This is also a positive factor, contributing to the realization of the Government's National Strategy on Green Growth and the development orientation of the green capital market of the Ministry of Finance. Therefore, when businesses seek independent third-party assurance, it will contribute to building the trust and credibility of stakeholders, and improve operational efficiency through process improvement, risk management. risk and seize the opportunity.
In fact, in the process of implementing assurance for Vinamilk's sustainability report, PwC Auditing Company will support to review the process, make recommendations and provide assurance for the report, in order to help This enterprise successfully implements sustainable development goals. In fact, not all auditing firms can meet the needs of enterprises, especially large enterprises, because there are audit units that do not have a department and consultant on sustainability reports.
Figure 3: Limited independent assurance report for Sustainability Report at Vietnam Dairy Products Joint Stock Company (VNM)
(Source: Vinamilk 's annual report, 2020) In Vietnam, Baoviet Holdings can be mentioned as a pioneer in successfully applying Internal Audit to ensure the criteria in the Integrated Report and Sustainability Report according to GRI standards. This is a division under the Board of Directors with the function of providing independent and objective assessments of the internal control system, risk management and corporate governance in the fields of business activities of the Group.
delegation to the Board of Directors and General Director on the basis of assurance and consulting activities. In order to ensure the reliability of some indicators in the 2016 Sustainability Report, Baoviet Holdings' Internal Audit Division has ensured a number of sustainability indicators. The Internal Audit Division provides an independent, objective assessment of the selected sustainability indicators and reviews PwC Vietnam's recommendations regarding the scope of the assessment based on established procedures. are specified in the Internal Audit Procedures and International Internal Audit Standards, guidelines published by the American Institute of Internal Auditors. This regulation requires the auditors of the Internal Audit Division to comply with professional ethics standards, risk- based assessment methods for the steps from planning, implementation to drawing conclusions. Based on 11 goals, Baoviet Group has selected from 17 sustainable goals of the United Nations, including 07 goals on building a sustainable society. The assurance services for a number of sustainability indicators in the 2016 Sustainability Report based on the Global Reporting Initiative's 2016 Sustainability Reporting Standards (GRI) include: GRI 401-1:
New hires and layoffs; GRI 404-1: Average training hours per year per employee; GRI 404-3:
Percentage of employees receiving periodic professional development and performance
appraisals; GRI 405-1: Diversity of management and staff; GRI 413-1: Local community engagement activities, impact assessments and development programs.
At the same time, recommendations to improve the reporting process and presentation of the Sustainability Report are also made clear such as: Composition of the sustainability report working group; Changes to the Sustainability Reporting standard; Training and guidance on the calculation and presentation of reporting indicators; Update the information collection form… Baoviet Sustainability Report 2016 is structured according to GRI standards which are clear and easy to understand with four main contents: GRI 101 General information; GRI 200 Economic issues; GRI 300 Environmental issues; GRI 400 Social issues and 33 specific indicators. With the message "I love the sea", Baoviet wants to convey the message of awareness of environmental protection, especially the marine environment, and at the same time arouse love for the homeland's sea and islands, towards sustainability through the prism. and the perspective of the children themselves - the future generation of the country. With this activity, once again, Baoviet continues to spread the awareness of environmental protection, ecosystem protection, towards sustainability of the whole community. By building a sustainable strategy from 17 sustainable goals of the United Nations, Baoviet has clearly demonstrated the integration of the world's sustainable goals in the development strategy of the business.
Figure 4: Report Assured by Internal Audit for Sustainability Reporting at Bao Viet Group (BVH)
(Source: BVH's Sustainable Development Report, 2020) Through actual research on the publication of sustainability reports at enterprises in Vietnam, enterprises are currently aiming to use a combination of internal audits or independent audits to ensure the quality of information on published reports. It can be seen that the audit units have strictly followed the audit principles, showing high professionalism
in their expertise to provide quality information on sustainability reports. Through the use of GRI international standards to provide assurance for sustainability reporting, the audit units reviewed the process, made recommendations and provided assurance for the report, to help businesses successfully achieve their sustainable development goals.