Justifying your accounting estimates

Jun 03, 2019
Accountants involved in preparing financial statements can expect increased scrutiny and challenge of their accounting estimates from their auditors.

I suspect that most accountants would agree that non-accountants believe the numbers in financial statements are more precise than they really are. Accountants, on the other hand, are much more conscious of the level of estimation that goes into many of those reported numbers. I must admit I didn’t become aware of the level of estimation involved until I entered the real world of auditing and accounting. I certainly don’t recall gleaning it from my accounting lectures or from the texts I read for my exams.

I spent many long days patrolling the aisles and shelves of warehouses and stockrooms torturing myself about the best estimate of just how much could be realised from excess and out-of-date lines of inventory, conscious that they had to be written down to their estimated selling price less estimated costs to complete and sell.  

What followed was long hours quizzing credit controllers while worrying about whether the 5% bad debt provision was the best estimate of the extent to which the amounts due from customers would not be collected, and whether the credit controller was too optimistic or too pessimistic.

Estimating the useful life of buildings and plant is key to the depreciation charge, an area of estimation where you might think an engineer would be more qualified than an accountant, though a futurologist might be better when it comes to the question of technological obsolescence.

On the liabilities side of the balance sheet, significant judgement is applied in estimating the amount of defined benefit pension obligations, including mortality and inflation assumptions, as well as assessing the likely outcome of legal claims and court cases, where the assumption about success or failure can be critical to the numbers included in the financial statements.

These are the some of the traditional areas of estimation uncertainty an accountant needs to consider. And, all of this was before the challenge of estimating value in use and fair values poked its head into so many areas of accounting. 

The implications of the new auditing rules for accountants in business

So, why is it appropriate to focus on estimation at this point? Well, since the issue of IFRS 9 and its emphasis on expected credit losses on loans and receivables upped the ante on estimation still further, auditing standard setters have seen fit to upgrade the rules on how to audit all types of estimates. Inevitably, as auditors direct more attention to estimates, accountants in business involved in financial reporting will feel the heat of incisive questions from their auditors as they apply the new rules to the myriad of estimates underlying the financial statements. 

The Irish auditing standard setter, the Irish Auditing and Accounting Supervisory Authority (IAASA), issued its new standard on auditing accounting estimates (ISA 540) in late 2018 with mandatory effect for audits of financial statements for periods commencing on or after 15 December 2019. That may seem some time away but, of course, early adoption of the more demanding rules is permitted, and some auditors may consider it appropriate to apply the new rules early. The implications of this for accountants in business are likely to vary significantly depending on the auditor’s assessment of the risk that incorrect estimation may cause a material misstatement.

Among the areas of particular focus in the updated ISA 540 is the requirement for the auditor to show adequate professional scepticism and to be on alert for management bias. 

There is also a strong emphasis on the auditor documenting – in detail – the management estimation process, including the assessment of material misstatement risks. The level of subjectivity underlying these estimates, and the degree of estimation uncertainty, will affect the design and completion of this process.

Of course, some auditors may have already been applying the new rules or, indeed, may have assessed that the new rules will not add to their audit effort. Accountants in business will wish to avoid any late surprises as a result of their auditor introducing additional audit procedures or placing increased demands on them.

It is worth remembering, too, that the auditor will seek written representations from management on certain matters, including areas of accounting estimation, and will often report to the board or the audit committee on areas of judgement and estimation, both of which can take up more senior audit effort. Further, for many listed companies, the auditor’s report to the shareholders will explain how the auditor has addressed significant estimates.

When the updated ISA 540 was being developed, many commentators, including some Irish auditors, had concerns that it might put an unnecessarily large burden on the audits of smaller companies. The final version of ISA 540 has attempted to allay those concerns by suggesting that the risk of material misstatement may be less significant in smaller companies with a consequent lower level of audit effort required. It will be useful for company accountants to be aware of where their auditor’s assessment of this risk lies along the spectrum and the consequences for the degree of audit effort required.

Preparing to justify accounting estimates

The degree to which the auditor decides it is necessary to devote effort and focus to the estimates can affect how accountants in business should prepare to justify their own estimates. That preparation might include more detailed documentation of the appropriateness of the estimates, the level of estimation uncertainty involved and the rigour of the internal control process surrounding the estimation process. This should help the auditor conclude on their reasonableness, and reduce the degree of effort spent drafting documentation they are required to complete. 

For some complex or specialised areas of estimation, company accountants may wish to ensure that their auditors have the necessary skills or expertise to assess the reasonableness of the estimates to reach their conclusions promptly. This may arise in areas such as actuarial assumptions for pension obligations, valuation techniques for derivatives and unquoted financial assets, the likely outcome of legal claims and uncertain tax positions, and technical provisions in insurance companies, to name a few.


There is no getting away from the vital role that estimation plays in financial reporting. Consequently, there can be no denying the importance of the auditor’s procedures in auditing those estimates, notwithstanding the level of interrogation and challenge this may entail as the auditor seeks to conclude on the reasonableness of the estimates. Clearly, it is desirable that maximum co-operation between management and auditor is achieved by early communication, explanation and clarity on the level and type of audit work planned, and the degree to which management and accountants in business can enhance their documentation of the estimation process.

After all, making accounting estimates is the prerogative of management, and management should have every opportunity to justify them to the auditors to ensure that the new, more onerous auditing rules neither add significantly to the cost nor disrupt the harmony of the audit.
Terry O’Rourke FCA is Chair of the Accounting Committee at Chartered Accountants Ireland.