When a CPA signs a federal tax return as the paid preparer, clients sometimes assume that signature means the CPA is vouching for everything on the document - that the numbers are right, the deductions hold up, and if something goes wrong, the CPA is on the hook. That assumption is wrong in ways that matter, and it is worth being direct about why.

The return belongs to the taxpayer

A federal tax return is a legal document signed by the taxpayer under penalty of perjury. That signature is a representation to the IRS that the information on the return is true, correct, and complete to the best of the taxpayer's knowledge and belief. It is not a formality. It is a sworn statement.

The preparer's signature is a separate and distinct representation - that the return was prepared based on information provided, and that the preparer has no knowledge that the return contains any position the preparer knew to be incorrect. That is not the same thing as vouching for the underlying facts. When the IRS examines a return, they are examining the taxpayer. The CPA is not the subject of that examination. The taxpayer is.

Why the two signatures mean different things

The taxpayer's signature under IRC Section 6065 is a declaration that the return is true, correct, and complete. The preparer's signature under IRC Section 6107 is a representation that the return was prepared in accordance with professional standards and that the preparer has no knowledge of incorrect positions. These are legally distinct obligations. Conflating them is a common misunderstanding with real consequences.

What the CPA is actually doing

The preparer's role is to apply the tax law to the facts as provided, identify available positions and elections, ensure the return is technically correct given the information in hand, and exercise professional judgment on positions that require it. That is a significant and skilled function. It is not the same as auditing the client's records.

A CPA preparing a return is not independently verifying that every fact the client represents is true. The relationship is built on a reasonable degree of trust in the information provided, combined with professional skepticism where the facts warrant it. The preparer is entitled to rely on client-provided information - that is not negligence. It is how the system is designed to work.

The difference between preparation and audit

An audit engagement requires independent verification of underlying records. A tax preparation engagement does not. The AICPA Statements on Standards for Tax Services (SSTS) explicitly recognize that a preparer may rely on information furnished by the client without independent verification, provided the preparer makes reasonable inquiry where facts appear incomplete, inconsistent, or implausible. Expecting a CPA to audit every client representation conflates two entirely different professional services.

Where the CPA's due diligence obligation begins

Professional standards under Circular 230 and the AICPA Statements on Standards for Tax Services (SSTS) require the preparer to make reasonable inquiries when information appears incomplete, inconsistent, or implausible on its face. This is not optional. It is a professional and ethical obligation.

In practice, this means that if a client claims a deduction or takes a position that is facially aggressive - or that does not pass a reasonableness check given what the preparer knows about the client's situation - the preparer has an obligation to ask questions, understand the basis for the position, and in some cases decline to take it. IRC Section 6694 imposes penalties on preparers who take unreasonable positions or act with reckless disregard for the rules, which is part of why that judgment matters.

What "reasonable inquiry" looks like in practice

Reasonable inquiry is not a checklist. It is a professional judgment call calibrated to the facts. For a straightforward W-2 return, very little inquiry is needed. For a return claiming Real Estate Professional status under IRC Section 469(c)(7), home office deductions, or a large vehicle expense, the preparer should understand the basis for the position - what records exist, whether the facts are internally consistent, and whether the numbers are plausible given the client's overall situation. The threshold for inquiry rises with the aggressiveness and dollar magnitude of the position.

Where due diligence ends: the CPA is not an auditor

Due diligence does not mean independently verifying every fact the client provides. The distinction is important and often misunderstood.

Take Real Estate Professional status as a concrete example. Qualifying under IRC Section 469(c)(7) requires that the taxpayer spend more than 750 hours in real property trades or businesses in which they materially participate, and that those hours exceed time spent in any other profession. If a client represents that they meet this test, the preparer's obligation is to understand the basis for that claim - to ask about the number of properties, the nature of the activities, whether a contemporaneous log exists, and whether the facts as described are plausible given the client's overall situation. The preparer is not required to audit the log line by line or demand corroborating records for every entry.

The same principle applies across the return. A client who represents that a vehicle was used 90% for business, that a home office is used exclusively and regularly for business, or that a deduction is properly substantiated - the preparer asks the right questions and applies professional judgment. The preparer does not conduct an independent investigation. That is the taxpayer's responsibility.

Real Estate Professional status: a closer look at the documentation burden

IRC Section 469(c)(7) is one of the most examined positions on individual returns. The IRS scrutinizes these claims heavily because the tax benefit - converting passive losses to active losses - is substantial. The taxpayer bears the burden of proving the hour requirements are met. Courts have consistently held that a contemporaneous time log is the most defensible form of documentation; reconstructed logs prepared at audit carry significantly less weight. The CPA's role is to advise the taxpayer on what documentation is needed and to assess whether the facts as represented are plausible. The CPA cannot create or certify records that the taxpayer did not maintain.

The client's documentation responsibility

The taxpayer is responsible for maintaining the records that support the positions on the return. The CPA can advise on what records should be kept, what a defensible position looks like, and what the IRS will expect to see in an examination. But the obligation to actually create and maintain those records rests entirely with the taxpayer.

If the return is examined, the IRS will ask the taxpayer - not the CPA - to produce documentation. Mileage logs, receipts, time records, lease agreements, bank statements - those are the taxpayer's records. Records that do not exist, cannot be located, or do not hold up under scrutiny are the taxpayer's problem. The CPA cannot produce documentation that was never created.

What the IRS actually asks for in an examination

In a correspondence or office examination, the IRS issues an Information Document Request (IDR) to the taxpayer. That request goes to the taxpayer directly - not to the CPA, except in a representative capacity. The taxpayer must produce the underlying records. The CPA, acting under a valid Form 2848 Power of Attorney, can represent the taxpayer and manage the process. But the records themselves must come from the taxpayer. A CPA who never received supporting documentation during preparation cannot produce it at examination.

What happens when a client provides incorrect information

If a client provides false or incomplete information and the preparer relies on it in good faith after making reasonable inquiry, the preparer's exposure is limited. The taxpayer's is not.

Accuracy-related penalties under IRC Section 6662 - which can reach 20% of the underpayment - attach to the taxpayer. Substantial understatement penalties attach to the taxpayer. In egregious cases, civil fraud penalties attach to the taxpayer. A preparer who exercised reasonable due diligence and relied on client representations has a defensible position under the reasonable cause and good faith defense in IRC Section 6664. A taxpayer who misrepresented facts to their CPA does not have the same defense available.

This is not a technicality. It is the actual legal framework. The taxpayer who tells their CPA that a deduction is legitimate when it is not has not transferred their liability to the CPA. They have compounded their problem.

The penalty structure in more detail

IRC Section 6662 imposes a 20% accuracy-related penalty on underpayments attributable to negligence, disregard of rules or regulations, or substantial understatement of income tax. A substantial understatement exists when the understatement exceeds the greater of 10% of the correct tax or $5,000 (confirm current thresholds on IRS.gov). IRC Section 6663 imposes a 75% civil fraud penalty when any part of the underpayment is due to fraud. These penalties attach to the taxpayer. The preparer faces a separate penalty regime under IRC Section 6694, but that regime does not reduce or eliminate the taxpayer's own exposure.

Aggressive positions: the preparer's role in pushback

When a client wants to take a position that the preparer views as unsupported or overly aggressive, the preparer has both a professional and ethical obligation to communicate that concern clearly. This means explaining the risk, explaining what documentation would be needed to support the position, and in some cases declining to prepare the return if the client insists on a position the preparer cannot in good faith sign.

That pushback is not the CPA being difficult. It is the CPA doing their job. Circular 230 requires preparers to exercise due diligence and prohibits them from taking positions with no reasonable basis. A preparer who signs a return containing a position they know to be unsupported is not protecting the client - they are exposing themselves to penalties under Section 6694 and potentially compromising their Circular 230 standing, while doing nothing to reduce the taxpayer's own exposure.

What "reasonable basis" and "substantial authority" mean for preparer standards

Circular 230 and IRC Section 6694 use specific standards to evaluate preparer conduct. A position has "reasonable basis" if it is arguable - roughly a 20% or better chance of being sustained on the merits. "Substantial authority" is a higher standard, requiring approximately a 40% or better likelihood of success. For positions that are not disclosed on the return, substantial authority is generally required to avoid preparer penalties. For disclosed positions, reasonable basis may be sufficient. These are not the same standard, and a CPA who conflates them is not applying the rules correctly. When a CPA declines a position, it is often because neither standard can be met on the facts as presented.

A shared document with asymmetric risk

Both the taxpayer and the preparer sign the return. The risk is not shared equally.

The taxpayer bears primary legal responsibility for the accuracy of the underlying facts. The preparer bears responsibility for the technical preparation - that the law was applied correctly to the facts as provided. When facts turn out to be wrong, the taxpayer is exposed first and most severely. Criminal and civil tax liability for underreported income or inflated deductions attaches to the taxpayer. The CPA's professional reputation and Circular 230 standing are at risk in a different and more limited way.

That asymmetry is not accidental. It reflects the underlying reality: the taxpayer is the one who knows what actually happened. The CPA is the one who knows how to report it correctly.

What this means in practice

A few plain-language conclusions follow from everything above:

  • Keep your records. The IRS will ask you for them, not your CPA. If they do not exist, no amount of professional preparation will fix that problem.
  • Be honest with your CPA. Misrepresenting facts does not transfer your liability - it creates a worse situation for you and limits your CPA's ability to protect you.
  • Understand that hard questions are protective. When your CPA asks you to substantiate a position, explain a number, or reconsider a deduction, that is not friction. That is professional judgment working in your favor.
  • Recognize what your signature means. Signing your return is a sworn statement. It is worth reading what you are signing and understanding the positions being taken on your behalf.

A good CPA relationship is collaborative. The CPA brings technical expertise and professional judgment; the taxpayer brings accurate information and the records to support it. Neither party can do their part without the other. But when something goes wrong, the legal framework is clear about whose name is on the document - and whose exposure comes first.

A note on the professional standards referenced here

Circular 230 (31 CFR Part 10) governs the practice of CPAs, attorneys, and enrolled agents before the IRS and sets the standards for due diligence, competence, and the positions a preparer may take. The AICPA Statements on Standards for Tax Services (SSTS) are the profession's own ethical standards for tax practice and address reliance on client-provided information, reasonable inquiries, and the preparer's obligations when facts are uncertain or incomplete. IRC Section 6694 imposes monetary penalties on preparers who take unreasonable positions or act with reckless disregard for the rules. IRC Section 6662 imposes accuracy-related penalties on taxpayers for underpayments attributable to negligence, substantial understatement, or similar failures. IRC Section 6664 provides the reasonable cause and good faith defense, which can reduce or eliminate those penalties when the taxpayer - or preparer - acted reasonably and in good faith. These are not obscure provisions. They are the operating framework for every federal tax return filed in the United States.