Reading time: 11 minutes
In the contemporary financial ecosystem, characterized by an increasing level of transparency, governance and reliability of information, auditors face a major responsibility: Provide an opinion based on sound evidence, documented and consistent with international standards.
In this regard, the International Standards on Auditing (ISA) is the essential benchmark for guiding the audit process, securing work and standardizing practices at the global level.
Some of these standards are central to the construction of operational audit records and techniques: ISA 501, 505, 510, 520, 530, 540, 550 and 580. They define essential due diligence, structure the collection of evidence, organise the execution of proceedings, guide the use of professional judgements and guarantee the quality of documentation.
Let us make an in-depth, clear and methodical synthesis of these obligations, so as to constitute a real work tool for auditors, collaborators, senior managers and accountants.
The technical basis of the audit file
Building an ISA-compliant audit record involves building on a coherent set of techniques, methods and controls that irrigate the entire mission. The Annual dossierin the same way as the permanent folder, should reflect a structured approach, based on entity understanding, risk identification, work planning, testing and finally opinion formulation.
The ISA standards discussed in this article thus cover most of the spectrum of due diligence:
- ISA 501 framework specific procedures on stocks, disputes and sectoral information.
- ISA 505 deals with external confirmations, the cornerstone of the reliability of third-party accounts.
- ISA 510 organises work on opening balances.
- ISA 520 formalizes the analytical procedures, essential for each audit phase.
- ISA 530 governs the use of surveys.
- ISA 540 framework the audit of accounting estimates.
- ISA 550 deals with related parties, a sensitive area par excellence.
- ISA 580 requires written statements from management.
Each of these standards plays a key role in creating a consistent, robust and justifiable record.
ISA 501: controlling specific evidence
ISA 501 is one of the most operational standards for the auditor, particularly when it comes to verifying the existence of stocks or assessing the reality of disputes. Physical observation of inventories is an essential step here. The auditor must be present during the countings, perform re-counting himself, evaluate internal procedures, verify deviations and ensure complete movements by fine cut-off analysis.
Disputes and court proceedings are another crucial part of this standard. External confirmations to lawyers, review of legal correspondence, assessment of associated provisions, and review of the entity's risks are key to assessing the quality of financial information.
Finally, ISA 501 recalls the importance of monitoring sectoral information when a company operates in several business segments in order to ensure consistency and relevance.
ISA 505: external confirmations, a major reliability tool
Circulation is one of the most reliable mechanisms for collecting high-quality evidence. ISA 505 strictly regulates the conditions for issuing, tracking and operating confirmation requests.
Auditors can use two main methods:
- Closed confirmation, widely used for customers and suppliers, allowing a standardized response on a specific balance.
- Open confirmation, intended for banks, lawyers and third parties whose response requires free and detailed expression.
The integrity of the process requires that letters be sent by the company and the replies received directly by the auditor, who must establish a mailing register, re-launches and a methodical analysis of responses or non-responses. These confirmations are essential to validate the reality of assets, liabilities, liabilities and litigation.
ISA 510: Work on opening balances
When an auditor intervenes for the first time in an entity, or in a change of auditor, consideration of opening balances is decisive.
The objective is threefold:
- verify that the anomalies of the previous financial year have been properly corrected;
- ensure that accounting policies have been appropriately extended;
- confirm that opening balances do not contain any significant anomalies that may affect the accounts for the year.
The auditor must carry out consistency tests, documentary checks, reconciliations with the N-1 accounts and, if necessary, reproduce or re-execute certain residual tests.
ISA 520: the central place of analytical procedures
An audit mission is based on an intensive and structured use of analytical procedures. ISA 520 formalizes the three basic types:
- preliminary analyses, intended to understand the entity, its environment and its risks;
- substantive analyses, to corroborate accounting balances ;
- Final analyses, necessary to assess the overall consistency of the financial statements before certification.
Preliminary analyses include study of variations, analysis of key ratios, comparison with previous years, sectoral benchmarks or financial modelling.
Substantial analytical procedures can sometimes, if sufficiently reliable and corroborated, replace piece tests. Finally, the final analyses validate the entire process and identify any residual inconsistencies.
ISA 530: Survey-based audit
For reasons of time and feasibility, the auditor cannot test all the elements of a population. ISA 530 therefore formally regulates the use of surveys, whether statistical or not.
The auditor shall:
- precisely define the auditable population;
- determine sample size according to service thresholds, sampling risk and professional assessment;
- select the elements according to a rigorous method (random, systematic, targeted);
- test selected items;
- extrapolate anomalies to the entire population;
- analyse the impact and decide on the necessary adjustments.
Comprehensive documentation is essential to justify the relevance and robustness of the approach.
ISA 540: Audit of accounting estimates
Accounting estimates now represent one of the areas at higher risk of significant anomalies. They involve judgements, assumptions, models, and are sometimes sensitive to management bias. ISA 540 therefore provides a comprehensive framework for the evaluation of these estimates.
The auditor shall understand the methods used, analyse the underlying data, perform independent recalculations, assess the relevance of the models, examine historical consistency through a retrospective review and ensure the adequacy of the assumptions chosen.
The most sensitive areas include:
- provisions for risks and charges;
- asset depreciation (recoverable value test);
- Financial instruments (fair value IFRS 9);
- provisions on receivables;
- tax estimates.
ISA 550: related parties, a major risk of manipulation
Transactions between related parties constitute a favourable ground for fraud, artificial transfers of profits, undocumented contractual arrangements or off-market transactions. ISA 550 therefore imposes extreme vigilance.
The auditor shall identify all related parties (organisations, statutes, contracts, regulated agreements), analyse transactions (prices, volume, economic justification), verify their completeness and ensure that the disclosures in the annex comply with the accounting requirements (in particular IAS 24 in IFRS).
This area requires a skeptical approach, as undeclared or atypical transactions can be meaningful and intentional.
ISA 580: written statements from management
The statement letter is an essential document for any audit engagement. It allows management to confirm in writing the completeness of the information provided, the absence of undisclosed facts, due diligence in litigation, the accuracy of estimates and the sincerity of the financial statements.
ISA 580 points out that these statements do not replace other audit techniques, but complement the evidence gathered and secure the auditor's position.
An operational matrix at the heart of the audit file
The consolidation of these standards allows for an effective programme of work. Each cycle: inventory, customers, suppliers, cash, capital assets, taxation, provisions, related parties, is framed by a coherent set of due diligences related to applicable standards.
This matrix is a strategic tool for firms, ensuring the quality of work, regulatory compliance, traceability and preparation of internal or external quality reviews.
A structured approach for a robust and compliant audit
The rigorous application of ISA 501, 505, 510, 520, 530, 540, 550 and 580 standards is an indispensable technical basis for any auditor wishing to deliver a reliable, documented opinion in accordance with international standards.
These standards, far from being mere formal obligations, structure the entire audit process, from learning to final certification. They provide a methodical framework, ensuring the quality of the work, the soundness of the evidence, the control of risks and the ability to demonstrate, in the case of control, the relevance of each professional judgement.
Baseline table for mission plan, programme of work and documentation
1. General (transverse) Diligences
| Standard | Diligence | Operational description | Parts/Livres |
|---|---|---|---|
| ISA 510 - Opening balances | Opening analysis | Review of opening entries, reconciliation with N-1 | Opening control sheet |
| Continuity of methods | Audit renewal of accounting principles | Memo of accounting principles | |
| Anomalies N-1 | Check corrections | Control of carryovers | |
| ISA 520 – Analytical Procedures | Preliminary analyses | Rates, variations, trends, risk identification | Preliminary analytical paper |
| Substantial analyses | Balance/activity correlation, operational ratios | Excel Corroboration Tables | |
| Final analyses | Overall consistency before opinion | Analytical conclusion memo | |
| ISA 530 - Audit surveys | Population definition | Accurate selection of audit basis | Population description |
| Sample size | Calculation by risk, threshold, significance | Survey spreadsheet | |
| Selection | Random, systematic, targeted method | List of selected items | |
| Implementation | Substantial tests on items | Worksheets | |
| Extrapolation | Extrapolation of observed anomalies | Extrapolation table | |
| Impact | Potential adjustments | Impact Memo |
2. Inventory cycle (ISA 501 - 520 - 530)
| Diligence | Description | Standards | Liquid |
|---|---|---|---|
| Physical observation | Presence in physical inventories | ISA 501 | Presence sheet, PV |
| Counting tests | Re-counting, sabotage tests | ISA 501 | Recounting forms |
| Inventory/ERP comparison | Reconciliation, variances | ISA 501 | Statement of variances |
| Cut-off tests | I/O analysis around the fence | ISA 501 | Cut-off sheets |
| Development | Method verification (FIFO/LIFO/CMUP) | ISA 501 | Calculation table |
| Rotation analyses | Rate and turnover | ISA 520 | Analytical table |
| Valuation surveys | Sampling on sensitive items | ISA 530 | Evaluation tests |
3. Customer cycle & turnover (ISA 505 – 520 – 530 – 540)
| Diligence | Description | ISA | Liquid |
|---|---|---|---|
| Circulation closed | Requests for confirmation of balances | ISA 505 | Register, replies |
| Cut-off tests | Sales close to closing | ISA 501, 520 | Cut-off sales slips |
| Asset review | Analysis of post-closure credit notes | ISA 520 | Excerpt from sales |
| Provision for doubtful accounts receivable | Estimation test and historical consistency | ISA 540 | Provision table |
| DSO analysis | Customer rotation, debt age | ISA 520 | Ratios + interpretation |
| Compliance tests | Verification of contractual conditions | ISA 530 | Part tests |
4. Supplier & Load Cycle (ISA 505 – 520 – 530)
| Diligence | Description | ISA | Liquid |
|---|---|---|---|
| Circularization suppliers | External confirmations | ISA 505 | Responses, register |
| Cut-off charges | Expenses payable, invoices not received | ISA 501 | Cut-off sheets |
| Compliance tests | Audit invoices, purchase orders, BL | ISA 530 | Test reports |
| Analysis of suspense accounts | Review of outstanding entries | ISA 520 | Suspense accounts |
| Rate of purchase | Trends, seasonality, margins | ISA 520 | Analytical procurement |
5. Capital cycle (ISA 501 - 530 - 540)
| Diligence | Description | ISA | Liquid |
|---|---|---|---|
| Physical Existence | Visits, site checks | ISA 501 | Visiting PV |
| Justification additions | Checking invoices, purchase orders | ISA 530 | Part tests |
| Amortization | Recalculations, consistency of durations | ISA 540 | Amortization table |
| Depreciation | Testing (IAS 36) | ISA 540 | Depreciation record |
| Cessations | Transfer PV analysis, plus/minus value calculation | ISA 530 | Substantial tests |
| Capital assets in progress | Attachment and cut-off | ISA 530 | Capital tests in progress |
6. Cash cycle & financial instruments (ISA 505 – 520 – 540)
| Diligence | Description | ISA | Liquid |
|---|---|---|---|
| Banking Circulation | Balance, guarantees, liabilities | ISA 505 | Responses banks |
| Bank reconciliations | Verification of letters | ISA 530 | FB reconciliation |
| Fund | Physical counts | ISA 530 | PV body |
| Financial instruments | Fair value tests | ISA 540 | IFRS 9 |
| Cash flow analysis | Consistency activity vs flow | ISA 520 | Cash flow analysis |
7. Cycle provisions & liabilities (ISA 501 – 540 – 580)
| Diligence | Description | ISA | Liquid |
|---|---|---|---|
| Litigation / lawyers | Open Circulation | ISA 501 / 505 | Legal Letter |
| Provisions for risks & charges | Evaluation of estimates | ISA 540 | File provisions |
| Off-balance sheet liabilities | Review of contracts, commitments | ISA 501 | Commitments |
| Post-event tests | Post-closure analysis | ISA 560 (recall outside perimeter) | Table EP |
8. Fiscal & social cycle
(Directly linked to ISA 520, 530, 540, 550, 580)
| Diligence | Description | Liquid |
|---|---|---|
| Reconciliation of taxes | Accounting/fiscal consistency control | Reconciliation table |
| Review of tax charges | Coherence by ratio and verification on parts | VAT/IS/CVAE tests |
| Social controls | Basis of calculation verification | Test pays |
| Tax provisions | Evaluations and estimation tests | Tax allowance sheet |
9. Transactions and related parties (ISA 550)
| Diligence | Description | Liquid |
|---|---|---|
| Identification of relationships | Organization charts, conventions | Related parties |
| Analysis of transactions | Price, lack of rationality, atypical flows | PL transaction sheets |
| Verification of disclosures | Annex, management report, IFRS | IAS 24 compliance table |
10. Statements and management writing (ISA 580)
| Diligence | Description | Liquid |
|---|---|---|
| Letter of affirmation | Written validation of management | Letter signed |
| Specific statements | Fraud, disputes, commitments | Reporting Annexes |
| Confirmation of completeness | Communication of all significant information | Completeness Form |
