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Errors in Source Documents: What an Audit Will Challenge and How to Correct the Document

Learn which primary-document errors are critical, their risks under CIS law, and how to correct them on paper and in EDI.

  • Mandatory source-document details: seven items under 402-FZ
  • Three classes of primary document errors
  • Fines and consequences: how a source-document error ends
  • Corrections in primary documents: the procedure under FSBU 27/2021

  1. A primary document is the basis for an accounting entry and proof of an expense.

  2. As long as it contains all mandatory details and they match the contract, payment, and accounting entry, the document is valid.

  3. When even one required detail is missing or conflicts with the other data, the company loses more than a piece of paper: it loses the expense, the deduction, and the accountant's time needed for recovery.

  4. Next: the most common primary-document defects, their cost under the Tax Code of the CIS, how to correct paper and EDI documents, and which checks to perform before posting rather than after period close.

Mandatory source-document details: seven items under 402-FZ

The mandatory details are defined in Part 2 of Article 9 of Federal Law No. 402-FZ “On Accounting.” There are seven, and the absence of any one makes the document disputable, regardless of how clear the transaction itself is.

Document detailWhat is checked in practice
Document nameThe document type is identified: act, delivery note, UPD, or report—it determines the form and accounting event
Date of preparationThe date is present, legible, and falls within the correct reporting period
Name of the economic entityThe document preparer is specified, not just the recipient's details
Substance of the business transactionA specific transaction is described rather than the vague wording “services under the contract”
Measurement value with unitsQuantity, price, amount, and unit of measure are specified and consistent
Positions of responsible personsIt is clear who performed the transaction and who is responsible for its documentation
Signatures with identifying detailsThe signature is accompanied by the surname and initials or other identifying information

The company head approves source-document formats: the required details matter, not a specific form. The exception is documents whose format is established by law: cash orders, invoices, and consignment notes. Their forms cannot be changed.

Three classes of primary document errors

Missing detail

The date, signature, signature details, unit of measurement, or description of the transaction is missing. The document does not formally confirm the business event, making the expense vulnerable during the first audit.

Data discrepancy

The details are present, but the amount, VAT rate, contract number, period, counterparty, or quantity differs from the contract, payment, specification, or accounting entry. The error passes visual inspection and surfaces during reconciliation.

Period error

The document is prepared correctly but arrives after the period closes or is dated for a month unrelated to the transaction. The expense is recorded in the wrong period, forcing the close to be reviewed.

The specific defects most often found in the document flow:

ErrorCritical for the expense or deductionWhat to do
The signature or signature details are missingYesRequest a corrected document from the counterparty
The preparation date is missing or illegibleYesCorrection with the correction date and signatures of the persons who prepared the document
The vague wording “services under the contract” without a description of the transactionYesRequest a document describing the specific transaction
The amount or quantity differs from the contract and specificationYesCorrected document; if the parties changed the terms, a corrective document
Incorrect VAT rate or amount on the invoiceYesCorrected invoice with the correction number and date
A typo in the counterparty’s name that does not prevent identificationNoCorrect in the normal workflow: this error does not prevent the deduction
An error in the contract number when the parties and amount are correctNoCorrect in the normal workflow
The document arrived after the period closedYes, for the periodRecord according to company policy: in the current period or by reopening the close

The first class is caught visually, the second only by matching the document against the contract, payment, and accounting entry, and the third through calendar controls and disciplined document collection. A “look and post” check catches only the first class: the other two defects are not visible in the document itself.

Fines and consequences: how a source-document error ends

Three provisions determine the cost of an error: - Article

CIS Tax Code requires documentary proof of the expense: if the document does not substantiate the transaction, the expense is excluded from the profit tax base. At the same time, Clause 3 of Article 54.1 of the Tax Code expressly states that formal defects in primary documents—for example, a signature by an unauthorized person—are not by themselves grounds for disallowing the expense if the transaction is real and was performed by a party to the contract. - Clause 2 of the article

CIS Tax Code distinguishes critical invoice errors from non-critical ones: if an error does not prevent the tax authority from identifying the seller, buyer, names of goods, works, or services, their value, the tax rate, and the tax amount, it is not grounds for denying a deduction. A denial is possible only for failure to meet the requirements of paragraphs 5, 5.1, and 6 of the same article—in other words, for an error that actually prevents identification. - Article

The CIS Tax Code penalizes the absence of source documents and systematic misstatement of transactions: $120 for a violation in one period, $350 for violations across several periods, and 20% of the unpaid tax, but at least $470, if the violation reduced the tax base. A source-document error rarely costs only one amount: a disallowed expense leads to additional tax, interest, and a penalty, while the corrected document must be requested from the counterparty and awaited.

Corrections in primary documents: the procedure under FSBU 27/2021

The correction procedure is set out in FSBU 27/2021, “Accounting Documents and Document Workflow.” It differs depending on the document medium.

The correction depends on how the document was created

  1. 01

    Paper document

    The incorrect text or amount is crossed out with a single line so the original value remains legible; the corrected value is written above it, along with the note “Corrected.”

  2. 02

    Correction details

    Any correction must include the correction date and the signatures of the people who prepared the document, with their positions, surnames, and initials.

  3. 03

    Electronic document

    The correction is made by preparing a new electronic document to replace the original: it states that it replaces the original, includes the correction date, and is signed with an electronic signature.

  4. 04

    Invoice and UPD

    An error that prevents identification is corrected with a corrected invoice or corrected UPD stating the correction number and date.

  5. 05

    Cash and bank documents

    Corrections are not permitted: this prohibition is established by clause 4.7 of Bank of CIS Directive No. 3210-U and clause 16 of Regulation No. 34n. The erroneous document is not amended; the transaction is documented again in accordance with cash-handling and banking settlement rules.

A separate case is a change in price or quantity agreed by the parties. This is not an error but a new transaction condition: it is documented with a correction document, not by correcting the original.

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Why manual checks fail to catch errors

  1. The accountant checks the document when posting it, amid a stream of dozens of files in which each counterparty submits its own format.

  2. Details appear in different places across templates; some documents arrive as scans, some through EDI, and some in correspondence.

  3. It is possible to match the amount to the contract, the VAT rate to the specification, and the period to the service date, but not for every document every day. As a result, the defect is found not on receipt, but at month-end closing, during reconciliation with the counterparty, or during a cross-check—when correction requires contacting the counterparty again and revisiting an already closed period.

  4. The impact on closing is covered in the article about errors when closing the month in 1C.

  5. Recurring reconciliation statement automation finds such a defect in the same month rather than a quarter later.

Pre-posting control

Checking pays off when performed as the document arrives, not after posting. The minimum checks for a primary-document workflow:

These nine checks require no judgment. They are deterministic: the data either matches or it does not. That is why they can be performed through a procedure rather than relying on attention.

How it works in KT.Team AI accounting

Within the AI accounting system, primary documents follow an executable workflow: the agent receives a document from an approved channel, extracts its details, checks them against the contract, reference data, and company rule, and creates an accounting document in 1C only after all checks pass. A document that fails validation is not posted; it goes to an exception queue with the reason and context, and the accountant makes the decision.

SOURCE DOCUMENT ROUTE STEP 1 · ACCESS The document arrived EDI, email, scan, or chat — only through an approved channel. The document format is flexible STEP 2 · DETAILS Data extraction Seven mandatory details under Part 2, Article 9 of 402-FZ. The required content matters, not the form STEP 3 · CHECKS Nine checks Contract, amounts, VAT, period, duplicates, basis, signatory. The decision is deterministic CHECKS PASSED Accounting document in 1C The agent creates and posts the document within an approved workflow and leaves an audit trail: inputs, checks, action, and rule version. CHECK FAILED Exception queue No posting is created. The accountant sees the reason and context, while the period is still open and the counterparty nearby—and makes the decision automatically. The defect is identified at intake, not during month-end closing or a counterparty audit.
Checks run before posting: the document either becomes an accounting entry or enters an exception queue with a reason.

This approach changes when the error is detected: the defect is visible on arrival, while the counterparty is available and the period is open, rather than a quarter later. The complete document workflow and checks are described on the page primary documentation, with the full role described on the page AI accountant, while a general overview of which accounting areas are delegated to the agent is provided in the article about AI in accounting.

FAQ

Frequently asked questions

Can a document be corrected with correction fluid or a new copy dated retroactively?

No. The original value must remain legible, and the correction must include the date and signatures of the people who prepared the document. An electronic document is corrected by issuing a new document to replace the original.

Does an error in a source document always disallow the expense?

No. What matters is whether the transaction and its parties can be identified from the document. An inaccuracy that does not prevent identification can be corrected; a missing mandatory detail makes the expense difficult to substantiate.

How does an adjustment document differ from a corrected document?

A corrected document fixes an error in the original data. A corrective document records an agreed change in price or quantity—it reflects a new transaction condition, not an error.

What should you do if the counterparty does not send a corrected document?

Record the request and status in a missing-documents register with an assigned owner and deadline. The register shows which expenses remain unsubstantiated before the period closes.

Can source documents be checked automatically when counterparties use different forms?

Yes. The required details and their compliance with the contract, reference data, and company rule are checked—not the form itself. A free-form document is acceptable except where the law prescribes an approved format.

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