Invoicing and internal audit: preparing your documents for review
Introduction
An internal audit is approaching and you're wondering whether your documents are in order. Missing invoices, inconsistent numbering, untraceable supporting documents: these situations create unnecessary complications during reviews.
In Switzerland, internal audits verify the compliance of your accounting and the traceability of your operations. Auditors examine your invoices, bank statements, VAT returns and all your financial documentation. Rigorous preparation saves you time and avoids awkward questions.
The good news: preparing for an audit doesn't require advanced accounting skills. You simply need to organise your documents methodically, verify their integrity and comply with legal archiving rules. Structured invoicing from the outset considerably simplifies this task.
This guide presents the essential documents to prepare, a 7-step checklist for organising your audit file, and common mistakes to avoid. You'll also discover how a structured invoicing solution facilitates traceability and reduces preparation time.
📌 Summary (TL;DR)
Preparing for an internal audit requires organised, complete and traceable documents. Gather your invoices issued and received, supporting documents, bank statements and VAT documents. Verify numbering, organise archiving by period, reconcile invoices and payments, and check tax compliance.
A structured invoicing solution like BePaid automatically centralises your documents, guarantees sequential numbering and facilitates bank reconciliation. You save time during reviews and comply with legal requirements for archiving over 10 years.
📚 Table of contents
Why internal audits require rigorous preparation
Internal audits verify the compliance of your accounting documents, detect errors and prepare for potential external reviews. It's an essential exercise for any business.
Disorganised documentation exposes you to real risks: tax penalties, VAT adjustments, considerable time wastage and unnecessary stress during inspections.
The key lies in structured invoicing from the outset. Rigorous day-to-day management greatly facilitates document preparation for audits and guarantees complete traceability of your transactions.
Essential documents to prepare for an audit
An internal audit requires complete and organised documentation. Here are the document categories to gather systematically to guarantee compliance.
Each type of document plays a specific role in verifying your accounting and must be easily accessible.
Invoices issued and received
Prepare all your QR-invoices compliant with Swiss standards, with continuous numbering and no interruptions. Also include client invoices and all supplier invoices received.
Compliance with Swiss standards is systematically verified during audits. Any anomaly in numbering or mandatory information will be noted.
Consult our guide on document retention to understand your legal archiving obligations.
Supporting documents and statements
Gather all your complete bank statements, expense reports with supporting documents, important commercial contracts and correspondence related to transactions.
Complete traceability is essential: every financial movement must be justifiable by a source document. Bank statements allow you to verify the concordance between your entries and actual flows.
Organise these documents chronologically to facilitate cross-checking during the audit.
VAT and tax documents
Prepare your quarterly or half-yearly VAT returns, purchase and sales registers, and all tax deduction supporting documents.
Verify the correct application of current rates: 8.1% (standard rate), 3.8% (special rate) and 2.6% (reduced rate).
Incomplete or incorrect VAT documentation leads to costly corrections. Each deduction must be supported by a compliant invoice with VAT mentioned.
Checklist: preparing your documents in 7 steps
Follow this practical checklist to methodically organise your documents before an internal audit. Each step guarantees a specific aspect of compliance.
Structured preparation considerably reduces audit time and limits the risks of detected anomalies.
1. Verify invoice numbering and integrity
Check that your invoice numbering is continuous, with no gaps or duplicates. Immediately identify any missing invoice and document the reason.
Verify that each invoice contains all mandatory information: complete contact details, VAT number if applicable, detailed description, amounts and dates.
This verification is a priority because discontinuous numbering systematically raises questions during reviews.
2. Organise archiving by period and category
Sort your documents by accounting period, then clearly separate income (client invoices) from expenditure (supplier invoices). Then classify chronologically.
Structured archiving facilitates quick retrieval of any document. Use clearly identified folders by year and type.
Discover the rules for certified electronic archiving according to the Olico ordinance for digital retention.
3. Reconcile invoices and payments
Verify the concordance between each invoice issued and its actual receipt. Do the same for invoices received and your disbursements.
Bank reconciliation is crucial for detecting discrepancies, missing payments or entry errors. It guarantees that your accounting reflects the reality of your cash flow.
Systematically document unpaid invoices or partial payments with their justification.
4. Check VAT and deductions
Review each invoice to verify the application of the correct VAT rate (8.1%, 3.8% or 2.6%). Ensure that all your deductions are justified by compliant invoices.
Prepare totals by rate to facilitate verification. A rate error, even minimal, multiplied over the year can represent a significant amount.
Deductions without compliant supporting documents will be systematically refused during a tax inspection.
5. Prepare documentation for special cases
Gather all credit notes issued, corrections made, cancelled invoices and credit memos. Clearly document the reason for each exceptional operation.
The traceability of corrections is essential: keep the original version and the corrected version, with justification for the change.
These special cases attract attention during audits. Complete documentation avoids suspicion and speeds up verification.
6. Verify readability and accessibility
Ensure that all your documents, paper or digital, are perfectly readable. Digitised documents must be in high resolution and correctly oriented.
Verify that you can quickly access any document. Archiving compliant with legal requirements must allow immediate consultation.
Learn how to scan your receipts correctly to guarantee their legal validity.
7. Create a summary file
Create a summary document with your key figures: total sales, purchases, VAT collected and deductible, number of invoices issued and received.
List the anomalies you've identified and corrected, with their impact. Prepare an index of available documents to facilitate navigation.
This summary file demonstrates your rigour and considerably speeds up audit work by providing a clear overview.
Traceability and legal archiving: rules to respect
In Switzerland, the law requires retention of accounting documents for 10 years. This obligation concerns all invoices, supporting documents, bank statements and VAT documents.
Traceability requires that each transaction can be reconstructed end to end: from the source document to the bank movement, via the accounting entry.
Since 2025, digital legal archiving has been recognised under strict conditions defined by the Olico ordinance. Documents must remain readable, unalterable and accessible throughout the legal period.
Consult our complete guide on your retention obligations for 10 years to understand all the details.
Failure to comply with these rules exposes you to sanctions during tax inspections, even if your accounting is otherwise correct.
Common errors that complicate audits
Certain errors frequently recur during internal audits and considerably slow down the verification process.
Discontinuous numbering: gaps in the invoice sequence without documented justification, immediately creating suspicion.
Missing invoices: documents lost or poorly archived, making complete verification impossible.
Incorrectly applied VAT: confusion between rates or incorrect application according to the type of service.
Disorganised archiving: mixed documents without structure, requiring hours of searching.
Absence of reconciliation: unidentified discrepancies between invoices and actual payments.
Illegible documents: faded thermal receipts, poor quality scans, corrupted files.
Anticipate these errors by implementing simple monthly verification procedures rather than correcting everything at audit time.
How BePaid facilitates preparation for your audits
BePaid automatically maintains compliant and organised documentation, greatly facilitating document preparation for your audits.
Automatic continuous numbering eliminates any risk of duplicates or gaps. Structured exports provide data ready for analysis.
Integrated bank reconciliation simplifies matching between invoices and payments. Centralised archiving guarantees immediate access to all your documents.
The QR-invoices generated are compliant with Swiss standards and contain all mandatory information. Payment tracking offers complete traceability.
BePaid doesn't replace an accountant but considerably facilitates preparatory work. Discover how to combine invoicing tools and accounting support.
Preparing your documents for an internal audit isn't an administrative formality. It's an approach that reflects the quality of your management and protects you in case of inspection. Coherent numbering, structured archiving, rigorous reconciliation between invoices and payments, and complete documentation of special cases: these elements constitute the foundation of effective preparation.
Traceability and compliance with legal obligations for retention for 10 years protect you from complications during audits. The most frequent errors, inconsistent numbering, missing documents, poorly documented VAT, can be avoided with methodical organisation.
BePaid supports you in this preparation by centralising your compliant invoices, automating numbering and facilitating the export of your documents. Create your free account and simplify the management of your accounting documents today.
