Understanding Tax Audits in Canada

By L.Kenway BComm CPB Retired
This is the year you get all your ducks in a row! Start by starting ... and keep it simple. Consistency beats perfection.

Updated April 27, 2026  |  Originally published on Bookkeeping-Essentials.com in 2011.

WHAT'S IN THIS ARTICLE
1. Introduction | What's New In 2026 | Start Here If ... | 2. Tax Review Process | 3. Tax Audit Process | Key Takeaway | Terms Used

NEXT IN SERIES >> CRA Audit Trails: Why you want them
BACK TO >> Self-Employed Audit-Ready Books

You have an email sitting in your Canada Revenue Agency (CRA) online portal. The heading is Notice of Reassessment. You feel your heart starting to beat a bit faster and wonder, "Did I screw something up?"

Start Here If ...

This page explains how CRA's review and audit process works ... what the notices mean, what triggers audit scrutiny, and what to do when CRA contacts you. Use the jump links to go straight to the section you need ...

 ... or you want to go deeper into related pages in this series.

Jump To >> Pre-Assessment Review | NOA | Processing Review | Matching Program | Recap

CRA Review vs. CRA Audit: Not the Same Thing

Not every letter from the CRA means you are being audited.

In many cases, the CRA starts with a review, not a full audit. A review is usually a request to confirm specific information on your return, such as deductions, credits, receipts, or other supporting documents. It is part of the CRA's normal compliance process.

A review also has an educational component. In many cases, the CRA is not only verifying the information filed, but also helping the taxpayer understand what records are required and how the rules apply. That said, a review should still be taken seriously. If you do not respond properly, or cannot support what you claimed, the result can still be adjustments, interest, penalties, or further scrutiny.

An audit is more serious and more detailed. If you are being audited, you will receive a notice explaining that you have been selected for an audit. Arrangements will then be made for a meeting to begin the audit.

That point matters. In an age of email fraud, phone scams, and cybercrime, you should know that a real audit is not something you are expected to guess at. The CRA will contact you and identify that an audit is beginning.

During an audit, the CRA may examine your books, source documents, bank records, invoices, receipts, and logs to verify that what you filed is accurate.

Why the difference matters
If you receive a review letter, do not ignore it just because it is 'not an audit'. Reviews can still lead to adjustments, interest, penalties, or further scrutiny if you do not respond properly or cannot support what you claimed.

If you receive an audit notice, do not assume you should handle it alone just because the request looks straightforward. Audits can involve nuances in what the CRA is really asking for, how records should be presented, and what follow-up questions your response may trigger.

When to get professional advice
If the CRA notifies you that you are being audited, consider speaking with an accountant or qualified tax professional before responding.

An audit request may look straightforward, but there may be issues or risks you do not recognize. Professional advice can help you decide how to approach the audit, what documents should be submitted, and how to avoid creating new problems through an incomplete or poorly framed response.

What to do now
If you receive any CRA letter:

1. confirm whether it is a review request or an audit notice
2. record the deadline immediately
3. keep the CRA reference number and include it in your response
4. gather the documents that support the amounts filed
5. keep copies of everything you send
6. if it is an audit, consider getting professional advice before responding
   

The Pre-Assessment Review

The pre-assessment review is part of CRA's normal processing of returns.

After you file your return, the CRA usually does a pre-assessment review before issuing your Notice of Assessment. AI does a quick check for arithmetic errors and checks various deductions and credits on the return. No manual reviews are done at this point.

If you file electronically, you may receive an Express Notice of Assessment (Express NOA) almost immediately through your tax software or CRA portal. That speed can be reassuring, but it does not mean CRA has finished validating everything on your return. Express NOA is a fast initial assessment, not a guarantee that the return will never be reviewed again.

Once this review has been performed, a Notice of Assessment (NOA) is issued. If you have a tax refund, it will be released at this time … but be aware that if the more detailed reviews determine there was an error, you may have to give some of that refund back … sooooo don’t spend it too quickly.

Practical reminder
If you know your return was rushed, based on incomplete records, or filed before all slips were received, do not assume an early NOA means the matter is over.

The peak period for pre-assessment reviews runs February to July ... tax season. But because this is 2026 and everything is being driven by AI, pre-assessment reviews could happen any time of the year.

The Notice of Assessment (NOA)

After you file your tax return, one of the first official documents you will receive from the CRA is your Notice of Assessment (NOA). It normally arrives about two (for electronic returns) to eight weeks (for paper-filed) after you file your return. If you eFile, you should get an Express NOA almost immediately in your My Account mail portal.

The NOA tells you how CRA processed your return at that point. If no problems were found, it confirms your numbers. If CRA made adjustments, the notice explains what changed ... and you may have additional tax, interest, or penalties owing.

If you disagree with the Notice of Assessment

If you believe the CRA made an error, DO NOT IGNORE IT.

Review the notice carefully and compare it to the return filed. If a professional prepared your return, contact them right away. CRA assessors can make mistakes.

You may need to file a Notice of Objection. You have until the later of:

• 90 days after the date on the Notice of Assessment, or
• one year after your filing due date (or June 15 if you are self-employed)

Don’t let that objection deadline expire because you have assumed the notice must be correct. As a general rule, CRA can reassess a return up to three years after the NOA was issued. That window extends to six years for returns involving carrybacks or investment tax credits ... and there is no limit at all if misrepresentation or fraud is suspected.

Review this list of moving CRA timelines based on the date of a document. It is your responsibility to be aware of these time frames.

The Processing Review

A processing review happens after your return has already been assessed. This is still part of the review process. It does not mean you are being audited.

This is a more detailed follow-up review than the pre-assessment check. At this stage, CRA may look more closely at specific deductions, credits, or claims and ask you to provide supporting documents such as receipts, invoices, mileage logs, schedules, or proof for credits claimed.

CRA uses processing reviews for two connected purposes ... to verify specific claims on your return, and to educate taxpayers about common areas of misunderstanding.

The educational intent has a practical consequence worth knowing. If you receive a CRA educational letter about unreported income or ineligible expenses, you may still be eligible to apply for the Voluntary Disclosure Program for partial interest and penalty relief. This is a significant change from previous rules where prompted applicants were generally not eligible. Talk to a tax professional if that situation applies to you.

A key change in 2026
Before April 2026, many processing reviews happened mainly after tax season. That is no longer a safe assumption. Effective April 2026, CRA is conducting processing reviews on a year-round basis. In other words, requests for supporting documentation can now show up at any time of year.

Why this matters
A processing review can feel unsettling because it arrives after you thought the return was already assessed. But this is exactly why you cannot assume an NOA means everything is final.

If CRA asks for supporting documents and you cannot provide it, the review may lead to denied deductions or credits, adjustments to your return, added tax, interest, possible penalties in some situations ... all the normal stuff!

What to do now
If you receive a processing review letter:

1. read it carefully
2. note the deadline immediately
3. locate the CRA reference number
4. gather the exact documents requested - no more, no less
5. keep copies of everything you send
6. respond completely and on time

If your tax preparer is authorized to receive CRA correspondence, they can view the letter through the Represent A Client portal. Remember, CRA deems a notice delivered once it hits your portal mailbox, whether you open it or not.

Practical tip

You can submit requested documentation electronically through My Account if you are registered, or through Represent a Client if you use a tax professional as your authorized representative.

The Matching Program

CRA's matching program compares the information on your tax return to information it receives from third parties such as employers, financial institutions, or platform economies. That includes things like:

• T-slips
• employer reporting
• financial institution reporting
• other mandatory information-sharing sources

In simple terms, CRA checks whether the income and credits reported on your return match the information it has already received from other sources. Its goal is to ensure the correct net income for tax purposes is reported … as many of Canada’s federal and provincial tax credits and benefits depend on this number.

The matching program typically runs after returns have already been filed and assessed. It typically runs between September and March. That is why a taxpayer may receive a Notice of Assessment, think everything is settled, and then later hear from CRA when the numbers do not line up.

An Example

You file your return, then receive an additional T-slip, usually a T3 or T5 for a self-employed worker, after the fact and never adjust your return. When CRA’s matching program compares what you reported against what the issuer reported, the discrepancy gets flagged.

For self-employed filers, unreported platform, gig, or sharing economy income is an increasing source of mismatches. See The Platform Economy for why CRA is paying close attention there.

The matching program can also work in your favour. If CRA finds that you under claimed certain amounts, such as some CPP-related credits or tax deducted at source, it may adjust the return and issue an additional refund where appropriate.

The bottom line
If CRA can match it, CRA can question it. It is always better to correct an error yourself than wait for CRA to find it first. The matching program is not about punishment. Its purpose is to make sure the return reflects the information CRA has on file so that Canadians get the benefits and credits they are entitled to.

Jump To >> How Returns Are Selected | What To Do Now Checklist | What Happens During An Audit | The Notice of Reassessment | If It Becomes a Dispute | Recap 

How Returns are Selected For A Tax Audit in Canada

Based on the pre-audit reviews above, your return may be selected for a more detailed tax audit. Understanding how that selection works has become important in 2026 because the process has changed significantly.

How Returns Have Traditionally Been Selected
For self-employed filers on a T1, returns may be selected for:

• comparison to third-party information - what you reported versus what CRA received from other sources
• missing information found under the matching program
• deductions or credits that appear unusual for the industry or filing situation, or CRA is actively monitoring
• prior audit history ... you were audited previously and it resulted in an adjustment
• random selection from CRA audit projects targeting taxpayer groups identified as having high non-compliance
• leads from other audits, investigations, or informants
• association with other taxpayers who were selected for audit

No distinction is made based on how the return was filed or who prepared it. Incorporated businesses follow a similar but separate selection process throughout the T2 corporate return.

What's Changed In 2026
CRA's AI audit systems are now operational. This changes the selection landscape in two important ways.

• The first is scale and speed. Automated screening algorithms now review millions of returns in real time flagging discrepancies and prioritizing files by risk level far faster than manual reviews ever could. For self-employed filers, this means your T2125 tax form is being benchmarked against industry norms at a scale that simply wasn't possible before.
• The second is lifestyle analysis. There has always been lifestyle analysis but now AI can aggregate data from multiple sources, not just your return and T-slips, to compare your reported income against your apparent lifestyle.

CRA has stated that its AI systems operate under human oversight. This means no audit action is taken based solely on algorithmic output. That's cold comfort if your records can't support what you filed.

The good news is CRA's AI systems are designed to identify patterns of non-compliance, error, and evasion ... not to catch honest taxpayers making reasonable claims. If your books are clean, and your documentation solid, AI driven selection means audit resources are directed at non-compliant filers rather than distributed randomly. That said, clean books in the age of AI driven audits demands a higher standard than it used to.

What this means in practical terms
Being selected does not automatically mean wrongdoing. It does mean something about the return, the reporting pattern, or the surrounding information caused the CRA to take a closer look.

That is why good recordkeeping matters so much. If your return is selected, you need to be able to show that the income reported, deductions claimed, and filings submitted are supported by proper records. If your records are weak, that is where a manageable issue can become a more serious one.

If your return is selected, it is the return itself ... and the supporting records behind it ... that matter. I've said it once but it bears repeating. No distinction is made based on how the return was filed or who prepared it.

Audit-Ready Checklist

What to do now
To reduce risk and improve your position if CRA asks questions later, look at this checklist to rate how audit-ready your books are before you file. Be honest with yourself. CRA's automated systems are designed to spot patterns, not to target honest small business owners with solid records. Ask yourself:

1. Yes or No? Have you reported EVERY dollar of income, including cash, e-transfers, and platform payments? Cross-check what you reported on your income tax return against what your HST/GST filings imply. If those two numbers tell different stories, the discrepancy will likely surface.
2. Yes or No? Do you have complete records? Avoid estimates or rounded claims unless you have the source documents to back them up. Reconstructing records after you receive a CRA review notice is stressful, expensive, and often incomplete. The documentation needs to exist before they ask.
   
3. Yes or No? Do your sources documents exist right now, before CRA asks for them? Keep receipts, logs, and source documents organized and accessible. This means mileage logs with business versus personal kilometres noted, home office floor plan measurements, utility bills, and meal or entertainment receipts with the business purpose written on them.
   
4. Yes or No? Can every deposit in your business account be traced and explained? Make sure deposits, invoices, and reported income can be traced and reconciled. Bank and credit card accounts should be reconciled monthly, not just at year end. Internal consistency is exactly what CRA's systems are checking for. Remember to document and track deposits from family & relatives. If you cannot prove that a transfer or deposit was a loan or a gift and not payment for services, CRA may count it as income.
   
5. Yes or No? Have you reviewed your unusual deductions carefully before filing ... and do you have the supporting documentation? Before you submit, compare your key ratios, things like expenses as a percentage of revenue or gross margin, against what is typical for your industry. If you are outside the norm, make sure you have a clear explanation ready and documented.
6. Yes or No? Are you using your business accounts as your personal money tree, taking a little bit here and little bit there? Keep personal and business finances completely separate. Commingled accounts are a red flag for automated review. When personal expenses flow through a business account, it raises the risk score on the entire file. Pay yourself regularly just like you would an employee.
7. Yes or No? Do you know when to get professional help? If your situation is complex, have a CPA review your return before filing. You don't know what you don't know.
   

Practical tip
Good records are your best protection in any CRA review or audit. If you are not sure what that looks like in practice, read >> How to Create CRA Audit Trails.

If you want to understand the most common issues that draw CRA attention, read >> What Triggers Tax Audits in Canada.

Office Audit vs. Field Audit: Not The Same Thing

If your return is selected for a tax audit, the auditor will conduct either an office audit or a field audit.

• An office audit (also called a desk audit) is handled from CRA’s office. You provide the requested documents ... today, usually by secure online submission, correspondence, phone, or email rather than an in-person visit. CRA doesn’t generally consider this a true audit; it sits closer to the review end of the spectrum.
• A field audit is more thorough. The auditor comes to your place of business ... or meets with your accountant or authorized representative ... at a pre-arranged time to examine your records in detail.
  
  A pre-arranged time and place matters. In an age of cybercrime, scams, and fake CRA contacts, you should know that a real audit does not begin with guesswork or panic. The CRA will contact you and identify that an audit is starting.
  

Either way, you will be notified in advance. This is not a surprise doorstep visit. If you have an accountant or authorized representative, they can meet with the auditor on your behalf. You don’t have to handle it alone.

Next step: Brush up on CRA’s business record retention requirements.

What Happens During A Tax Audit In Canada?

The auditor’s purpose is to verify that the income reported, deductions claimed, and tax filings submitted are accurate and backed by records. During an audit, the CRA may examine records such as:

• ledgers and journals
• bank statements and deposit records
• sales invoices and expense receipts
• contracts and agreements
• GST/HST records
• payroll records
• mileage logs and other supporting schedules

Any unsupported claims will usually be denied. Storing your tax returns and supporting documents in one place each year will make a future audit proceed smoothly … no running around trying to gather information …

… soooo remember to put back any pieces of paper you remove from your bookkeeping box … otherwise you undo all your audit-proofing efforts. :O( The better option these days is to store your documents in the cloud using a document management system.

As I said, any unsupported claims will usually be denied. If your records are weak, incomplete, inconsistent, or unsupported, adjustments ... plus interest, and penalties ... follow. That means you will likely also owe more tax.

An audit is not cause for alarm in itself. It is a compliance process. If your records are organized and your filing is supportable, the audit may simply confirm that your reporting is in order. Where audits become serious is when there are weak records, unsupported claims, underreported income, or tax avoidance or tax evasion.

It also helps to remember that the auditor is a human being. First impressions matter. One of the best first impressions you can make is to provide well-organized records, clearly labeled documents, and the information requested. That tells the auditor you take the process seriously and are prepared to support what you filed. It starts the audit on a good path.

The auditor will make proposals during the audit. Always ask for those proposals in writing. You’ll have 30 days to respond, and your response will be considered before any reassessment is issued.

Do not treat an audit casually

An audit is not the time to guess, fill gaps from memory, or send documents without thinking through what they show.

Even when the CRA request appears straightforward, there may be nuances in:

• what the CRA is really testing
• how documents should be organized and presented
• what new questions your response may trigger
• whether a document helps your position or weakens it

When to get professional advice
If you are being audited as opposed to being reviewed, it would be prudent to contact an accountant or qualified tax professional before you respond. A professional can help you assess the scope of the audit, decide how to approach it, determine what documents should be submitted, and communicate with CRA more effectively.

What happens as the audit moves forward
As the audit progresses, the auditor may raise issues or propose adjustments based on the records reviewed. You are generally given an opportunity to respond before a reassessment is finalized. When that happens, your accountant will:

• ask for proposals or concerns to be put in writing,
• review them carefully and discuss them with you,
• respond within the deadline given, and
• provide support for your position where possible.

The Notice of Reassessment (NOR)

Part 1. NOR Is Issued

If the audit results in changes to your return, CRA will issue a Notice of Reassessment (NOR). Like the original NOA, this is an official document ... keep it with your records.

If you disagree with the reassessment, the same objection process applies. You have until the later of 90 days from the reassessment date or one year from your original filing due date to file a Notice of Objection. Don’t let that deadline slide.

For more details on what to do after an audit notice arrives ... including your rights as a taxpayer:

Jump To >> Responding to a Tax Audit Notice

Jump To >> Taxpayer Bill of Rights

A NOR can also be issued when the CRA changes a return that has already been assessed. This can happen after:

• a review
• a matching program adjustment
• an audit
• an amendment request
• new information coming to the CRA's attention

Remember, a reassessment means the CRA has revisited the return and changed one or more amounts. That change may result in:

• more tax owing
• added interest
• penalties
• or, in some cases, a refund if the correction is in your favour

Part 2. Why Deadlines Matter

Why a reassessment should never be ignored
A reassessment is NOT routine paperwork. It is a signal that the CRA has changed your file. If you receive one, you need to understand:

• what changed
• why it changed
• whether the change is correct
• what deadline applies if you want to challenge it

If you agree with the change, deal with any balance owing promptly to reduce additional interest. If you disagree, act quickly. Deadlines matter.

How long CRA can usually change a return
As a general rule, the CRA can usually reassess a return for up to three years after the original Notice of Assessment is issued.

You may hear this referred to formally as the statute of limitations. In practical terms, it is the usual time limit for how long CRA has to go back and change a return.

That time limit can be longer in some situations. For example:

• if there is suspected misrepresentation or fraud, there may be no time limit
• if the return involves items such as carrybacks or investment tax credits, the period may extend to six years

Why these time limits matter
Many taxpayers make one of two mistakes:

• they assume a Notice of Assessment means everything is final
• they miss the objection deadline because they do not realize the clock is already running or haven't checked their CRA email portal regularly.

Both mistakes can be costly.

If you disagree with a reassessment
If you believe CRA made an error, do NOT set the notice aside and hope to deal with it later. Read it carefully. Compare it to the original return, the supporting documents, and any earlier CRA correspondence.

If a tax professional prepared the return or helped you respond to CRA, contact them right away. CRA assessors can make mistakes, and objection deadlines should never be allowed to expire while everyone assumes the notice must be correct.

A quick note on objections and appeals
If you disagree with the reassessment, you may need to file a Notice of Objection within the allowed time.

If the matter continues beyond that stage, there is also an appeal process through the courts.

Tax audits in Canada have an appeal procedure. You can find great pictorial overviews of both the informal procedure and general procedure for notices of appeal on the Tax Court of Canada website. See what happens after filing the first document. Please click because it is worth reading.

What to do now
If you receive either notice:

1. read it carefully
2. identify whether CRA accepted or changed your return
3. note any deadline immediately
4. keep the notice with your tax records
5. compare the notice to the return filed
6. if something looks wrong, get advice before the deadline expires

Related reading >> Relevant Moving Timelines

Part 3. If Your Dispute Escalates

If the CRA Appeals Division denies your objection, you can appeal to the Tax Court of Canada (TCC). There are two possible procedures:

1. Informal Procedure
Think of this as the tax version of small claims court. This process is simpler than a full court action. There are no filing fees, the rules of evidence are more relaxed, and you may represent yourself or use an accountant. Costs are rarely awarded against you. It is generally available when:

• the federal tax and penalties in dispute are $25,000 or less per assessment
• the disputed loss is $50,000 or less
• or only interest is in dispute

2. General Procedure

This is used when the dispute is larger or more complex.

It involves stricter court rules, formal procedures such as examinations for discovery, and filing fees. While an individual may represent themselves, a corporation must use a lawyer. Decisions under this process can also set legal precedents.

Why this matters
Most taxpayers never want to get this far. That is exactly the point. The earlier you respond properly, keep good records, and deal with problems before they harden into disputes, the better your chances of avoiding a long and expensive fight.

If you want to know more
The Knowledge Bureau, a respected Canadian financial education institute since 2003, still have 2 excellent articles on their site discussing the 2 choices above.

I've updated the monetary limits in square brackets. The October 24, 2012 article looks at the formal tax court procedure while the November 4, 2012 article titled Sometimes it’s all about the proper procedure looks at the pros and cons of the informal procedure which is less costly and less time consuming. I still like these articles because they explain your options clearly and simply.

The October 24, 2012 article titled Tips From Tax Court: Procedures for Objecting Taxpayers very briefly provides an overview of both procedures. Here is an excerpt:

"The Informal Procedure is available only if the total disputed tax amount (other than interest or provincial tax) does not exceed $12,000 [$25,000 since 2013; $50,000 for GST disputes - before 2013 no limit], the amount of loss in issue does not exceed $24,000 [$50,000 since  2013], or the only amount disputed is interest ...

General Procedure is a formal litigation process that begins in the Tax Court of Canada and can proceed, if unresolved, through the Federal Court of Appeal right up to the Supreme Court of Canada. Going through this general court process is usually lengthy — there is no pre-determined time frame and can take several years — and very costly. It applies to disputes in which federal taxes exceed $12,000 [$25,000 since 2013; $50,000 for GST disputes - before 2013 no limit]."

Key Takeaway

Reduce your fear of tax audits by understanding the process. It is your responsibility to have knowledge of and apply the tax laws correctly, whether your return was prepared by a professional or not.

In Canada, we have a self assessing and self-reporting tax system. If you are caught evading tax, it is a criminal offense. Under tax law (unlike criminal law), you are guilty until proven innocent.

Small business owners have a higher likelihood of getting audited than an employee because they have to remit their own source withholdings. Possible types of tax audits a small business owner may be subjected to are Office, Field, GST HST, or Payroll.

In 2026, due to CRA AI processes, the bar for what 'good records' means has moved up. It is more important than ever to have up-to-date books and organized records. Audit proof books are your best defence.

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