Auditing and Ethics · Audit Evidence

Audit Evidence: Meaning, Nature and SA 500

Updated 4 October 2026 · Fact-checked

Audit evidence is all the information the auditor uses to reach conclusions on which the audit opinion is based. SA 500 requires evidence that is sufficient (enough in quantity) and appropriate (relevant and reliable in quality). To answer questions, define the term, apply both tests, and judge reliability by source.

Understand Audit Evidence: Meaning, Nature and SA 500

Audit evidence is the information an auditor uses to form the audit opinion. It includes information in the accounting records underlying the financial statements and other information. Think of it as the proof behind every statement in your report. Without it, the opinion is only a guess.

Evidence comes from two broad places. Accounting records include the ledgers, journals, vouchers, invoices, contracts, bank reconciliations and supporting spreadsheets. Accounting records alone do not provide sufficient appropriate audit evidence on which to base an opinion, so the auditor must obtain other information as well. Other information includes confirmations from third parties, inspection of assets, observation of inventory counting, inquiries of management, analytical procedures and information from experts. The auditor needs both kinds.

SA 500 says evidence must be sufficient and appropriate. Sufficiency is the measure of the quantity of evidence. Appropriateness is the measure of its quality, that is, its relevance and reliability. The two are linked. The quantity needed depends on the assessed risk of material misstatement (the higher the risk, the more evidence is needed) and on the quality of the evidence (the higher the quality, the less may be required). More evidence may not compensate for poor quality.

Reliability depends on the circumstances. In general, evidence is more reliable when it is obtained from independent external sources, when the auditor obtains it directly rather than indirectly or by inference (for example, by inquiry), when it exists in documentary form and when it is an original document rather than a photocopy or fax. Direct evidence such as inspection is more reliable than indirect evidence such as inquiry. These are general rules, not fixed ones. For example, external evidence can be less reliable if the source lacks independence or knowledge.

Keep one more point separate from the external-versus-internal comparison. When evidence is generated internally by the entity, it is more reliable when the related controls, including those over its preparation and maintenance, are effective. This is a test of internally generated evidence. It does not rank internal evidence above or below external evidence.

The auditor designs and performs audit procedures that are appropriate to the purpose. SA 500 also deals with information used as evidence, such as information produced by the entity, where the auditor must evaluate its accuracy and completeness, and with selecting items for testing. If evidence from one source is inconsistent with another, or doubts arise about its reliability, the auditor determines what changes or additions to procedures are needed and considers the effect on other parts of the audit.

Key rules to remember

Definition of audit evidence: Audit evidence = information used by the auditor to arrive at conclusions on which the audit opinion is based; Includes accounting records and other information. Write both in your answer.
Core requirement of SA 500: Evidence must be sufficient AND appropriate; Both are needed. Sufficient is about quantity. Appropriate is about quality.
Appropriateness: Appropriateness = relevance + reliability; Relevance links to the assertion tested. Reliability depends on source, nature and circumstances.
Link between risk and quantity: Quantity needed depends on assessed risk of misstatement and on quality of evidence; Higher risk needs more evidence. The higher the quality, the less may be required. More evidence may not compensate for poor quality.
Reliability guide: Generally: independent external sources > internal sources; direct > indirect; documents > oral; originals > copies; These are general rules, not always true. Reliability depends on circumstances. Separately, internally generated evidence is more reliable when the related controls are effective.
Procedures to obtain evidence: Inspection, observation, external confirmation, recalculation, reperformance, analytical procedures, inquiry; Inquiry alone is not sufficient to support an assertion.

How to solve Audit Evidence: Meaning, Nature and SA 500 questions

Use this method for theory questions on meaning, sources, sufficiency, appropriateness or reliability.

1Read the question and identify what is asked: definition, sources, reliability comparison or sufficiency versus appropriateness.
2Define audit evidence in one or two lines, naming SA 500 and mentioning accounting records and other information.
3State the two tests: sufficiency (quantity) and appropriateness (relevance and reliability).
4Apply the point to the facts given. For a comparison, rank the items by source, form and directness, and say why.
5Link the amount of evidence to assessed risk and to the quality of the evidence.
6Mention what the auditor does if evidence is inconsistent or doubtful: modify or add procedures and consider the effect on the audit.
7Finish with a one-line conclusion that answers the question directly.

Quickest way: Two-test shortcut for MCQs and written answers

When to use it: Use it when time is short or when an MCQ gives you evidence types and asks which is more reliable or what the term means.

MCQ: Ask 'Is this about quantity or quality?' Quantity points to sufficiency. Quality, relevance or reliability points to appropriateness.
MCQ reliability: Pick the option that is external, direct, documentary and original. Check whether the circumstances override this.
MCQ trap: An option saying more evidence can compensate for poor quality is wrong.
Written: Open with the SA 500 definition, then use two sub-headings, Sufficiency and Appropriateness.
Written: Give two or three reliability points with a short reason each, since step marks follow the points.
Close by linking to risk and professional judgment.

Common mistakes in Audit Evidence: Meaning, Nature and SA 500

Treating sufficiency and appropriateness as the same thing.
Both sound like 'enough proof' and students blur them.
Fix: Remember: sufficiency is quantity, appropriateness is quality. Appropriateness has two parts, relevance and reliability.
Saying a large volume of evidence can make up for poor quality.
Students assume more is always better.
Fix: State that higher risk needs more evidence, but quantity cannot cure poor quality.
Claiming inquiry alone is enough to support an assertion.
Inquiry is easy and common, so it feels adequate.
Fix: Say inquiry is usually corroborated by other procedures and is not sufficient on its own.
Stating that external evidence is always more reliable than internal evidence.
Students memorise the ranking as an absolute rule.
Fix: Use words like 'generally'. For example, external evidence may be unreliable if the source lacks knowledge or independence.
Limiting audit evidence to accounting records and vouchers.
Vouchers are the most familiar evidence in practice.
Fix: Always list accounting records and other information such as confirmations, inspection, observation and expert reports.
Ignoring the reliability of entity-produced information.
Students accept reports from the entity's system at face value.
Fix: Add that the auditor evaluates whether such information is accurate and complete enough for the audit's purpose, and that internally generated evidence is more reliable when the related controls are effective.

Worked examples

Example 1

Distinguish between sufficiency and appropriateness of audit evidence under SA 500. Can an auditor offset poor-quality evidence by collecting more of it?

Show the solution

Audit evidence is the information used by the auditor to reach the conclusions on which the opinion is based.
Sufficiency is the measure of the quantity of audit evidence. The amount needed depends on the assessed risk of material misstatement and on the quality of the evidence.
Appropriateness is the measure of the quality of audit evidence, that is, its relevance and reliability in supporting the conclusions.
Relevance means the evidence relates to the assertion being tested. Reliability depends on source, nature and circumstances, for example external, direct, documentary and original evidence is generally more reliable.
The two are related: higher risk calls for more evidence, and the higher the quality of the evidence, the less may be required.
However, more quantity may not compensate for poor quality. Unreliable evidence stays unreliable however much of it is collected.

Answer: Sufficiency concerns quantity and appropriateness concerns quality (relevance and reliability). An auditor cannot offset poor-quality evidence by collecting more of it.

Example 2

During the audit of a company, the auditor can verify a debtor balance either through a confirmation received directly from the debtor or through a photocopy of the invoice provided by the company's accountant. Which is more reliable and why?

Show the solution

Identify the two sources: a direct external confirmation and an internal photocopied document supplied by the entity.
Apply the SA 500 reliability guide: evidence from independent external sources is generally more reliable than evidence from internal sources.
Evidence obtained directly by the auditor is generally more reliable than evidence obtained indirectly through the entity.
Original documents are generally more reliable than photocopies, which are a weaker form of evidence.
On source, directness and form, the confirmation is generally more reliable than the photocopied internal invoice.
This is a general conclusion, not an absolute one. The confirmation's reliability is reduced if it is not received directly by the auditor, for example if it passes through the entity first, or if the respondent lacks independence or knowledge of the matter. In that case the auditor performs further procedures.

Answer: The direct external confirmation is generally more reliable because it comes from an independent external source and is obtained directly by the auditor, unlike a photocopied internal invoice supplied through the accountant. Its reliability would fall if it were not received directly by the auditor or if the respondent lacked independence or knowledge.

Exam tips

Start every theory answer with the definition and the words 'sufficient and appropriate'. Examiners look for them.
Use two short headings, sufficiency and appropriateness, and put one clear point under each.
For reliability questions, give a ranked list with a reason for each ranking, and add 'generally' to avoid overstatement.
MCQs often test whether a statement is true or false. Watch for words like 'always' and 'only'.
Attempt every MCQ since there is no negative marking. Eliminate absolute statements first.

Practice questions from Audit Evidence

Audit Evidence: Meaning, Nature and SA 500 in other exams

The same ground in other exams, if you are preparing for more than one or want another angle on it.

Audit Evidence: Meaning, Nature and SA 500: frequently asked questions

What is audit evidence in simple words?

Audit evidence is the information the auditor collects to support the opinion on the financial statements. It includes accounting records and other information such as confirmations, inspection and observation.

What is the difference between sufficiency and appropriateness of audit evidence?

Sufficiency measures the quantity of evidence. Appropriateness measures its quality, which means its relevance and reliability. The auditor needs both to support the opinion.

Does SA 500 say more evidence can make up for poor quality?

No. The quantity needed is affected by the assessed risk and by the quality of the evidence. But more evidence may not compensate for poor quality.

Which type of audit evidence is most reliable?

Generally, evidence from independent external sources, obtained directly by the auditor, in documentary and original form, is most reliable. This depends on circumstances, so always qualify the statement.