What Your Notice of Assessment Actually Tells You (And What to Watch For)

You filed your tax return in April. A few weeks later, an envelope arrives from CRA. Your Notice of Assessment.

Most Ontario business owners open it, look at one number—refund or amount owing—and set it aside.

If they’re getting money back, they’re satisfied. If they owe money, they pay it. Either way, the NOA usually goes in a file and doesn’t get looked at again.

Here’s the problem: your Notice of Assessment contains significantly more information than just your refund or balance owing. It shows what CRA accepted, what they changed, what they’re carrying forward, and what might trigger issues down the line.

At KKCPA, May is when we review clients’ Notices of Assessment. Regularly, we find discrepancies, errors, or concerning adjustments that clients missed because they only looked at the bottom-line number.

Some discrepancies are minor. Others are significant—affecting future years, benefits, credits, or creating problems that compound if not addressed.

Here’s what Ontario business owners need to understand about their Notice of Assessment and why the refund amount isn’t the only thing that matters.

What a Notice of Assessment Actually Is

When you file your tax return, CRA doesn’t just accept it as filed. They process it, review it, and issue a Notice of Assessment showing their determination of your tax situation.

What the Notice of Assessment tells you:

What you reported vs. what CRA assessed. Your refund amount or balance owing. Your RRSP deduction limit for next year. Amounts being carried forward to future years. Any changes CRA made to your return. Your assessment date and reassessment rights.

What the NOA doesn’t explicitly tell you:

Why CRA made changes (if they did). Whether those changes are correct. Whether you should accept them or question them.

The distinction:

Your tax return is what you filed. Your Notice of Assessment is CRA’s response to what you filed. These aren’t always identical.

Most business owners assume if CRA issued an NOA, everything must be correct. That’s not always true.

The Numbers Most Business Owners Actually Look At

When business owners open their Notice of Assessment, they look for specific information.

What everyone checks:

Refund or balance owing: The most prominent number. If you’re getting $3,000 back, that’s what registers. If you owe $5,000, that’s what you focus on.

RRSP deduction room: Many people check this to know their contribution limit for next year.

That’s usually where review stops.

The problem: these numbers might be correct, but other information on the NOA might indicate issues that will create problems later.

A refund doesn’t mean CRA accepted everything you claimed. They might have reduced deductions but other factors still resulted in a refund. You got money back, so you don’t notice they disallowed $10,000 in expenses.

What CRA Changed (And Why You Need to Know)

If CRA made changes to your return, the NOA will show this—but not always obviously.

Where changes appear:

Summary section comparing what you reported to what was assessed. Detailed breakdown showing line-by-line adjustments. Sometimes explanatory notes (though these are often cryptic).

Common changes CRA makes:

Information slip mismatches: You reported $50,000 in T4 income. CRA has records showing $52,000. They adjust to match their records.

Disallowed or reduced deductions: You claimed $15,000 in business expenses. CRA reduced this to $12,000 without explanation (they may send separate letter requesting documentation).

Benefit or credit adjustments: You claimed a specific credit. CRA determined you don’t qualify and removed it.

Calculation corrections: Math errors in your return that CRA corrected.

Why this matters:

If CRA changed something significant and you don’t notice, you might:

Not understand why your refund is smaller than expected
Miss that they’re questioning certain deductions (which might trigger information requests)
Fail to correct an error that will affect future years
Not realize you have grounds to object if the change is wrong

The problem:

Many changes aren’t accompanied by detailed explanation on the NOA itself. You see the adjusted number but not why CRA made the adjustment.

This is particularly problematic when CRA’s change is incorrect. If you don’t catch it, you’ve accepted an assessment that’s wrong.

The Carry-Forward Amounts That Shape Future Years

Your NOA shows amounts being carried forward to future tax years.

Common carry-forwards:

RRSP deduction room: Your contribution limit for the next year.

Capital losses: Investment losses you can use to offset future capital gains.

Non-capital losses: Business losses that can be applied to future years’ income.

Tuition and education amounts: Unused credits carried forward.

Charitable donation carry-forwards: Donations you didn’t claim this year that you can claim in future years.

Why these matter:

These amounts directly affect your future tax planning. If they’re wrong, every future return built on them will also be wrong.

Example:

Your NOA shows $20,000 in capital loss carry-forward. You think you have $30,000.

Next year, you have a $25,000 capital gain. You plan to use your $30,000 loss carry-forward to offset it completely.

But you only have $20,000 according to CRA. You’ll owe tax on $5,000 of the gain that you thought would be covered.

The verification problem:

Most business owners don’t verify carry-forward amounts. They assume CRA calculated them correctly.

Sometimes CRA’s records are correct and yours are wrong. Sometimes yours are correct and CRA’s are wrong. Sometimes both are wrong for different reasons.

Without verification, you won’t know until you try to use the carry-forward in a future year and discover the discrepancy.

When Your Refund Doesn’t Match What You Expected

You filed your return expecting a $5,000 refund. Your NOA shows $3,000.

Most common reactions:

“I must have miscalculated.” “CRA knows better than me.” “At least I’m getting something back.”

What you should actually do:

Figure out why there’s a $2,000 difference.

Possible reasons:

CRA reduced or disallowed deductions you claimed. You had an outstanding balance from a previous year that CRA applied to this year’s refund. You owe instalments that CRA deducted. CRA corrected errors in your calculations. CRA has information about income you didn’t report (information slips you missed).

Why the reason matters:

If CRA reduced deductions because you made an error, you need to know what error so you don’t repeat it.
If CRA reduced deductions incorrectly, you might have grounds to object.
If they applied your refund to old debt, you need to understand what that debt is and whether it’s correct.

The cost of not investigating:

You accept a $2,000 reduction that was actually incorrect. Or you don’t realize CRA is questioning certain types of expenses, so you claim them again next year and face the same reduction—or worse, an information request or audit.

The Reassessment Timeline You Need to Know

Your NOA includes an assessment date. This date is critical because it starts the clock on your right to object.

The rule:

You have 90 days from the date on your Notice of Assessment to file an objection if you disagree with CRA’s assessment.

Not 90 days from when you received it. Not 90 days from when you opened it. 90 days from the date printed on the NOA.

Why this matters:

If you set aside your NOA without reading it carefully, weeks might pass. By the time you realize there’s a problem, you might have limited time to object—or the deadline might have already passed.

What happens if you miss the 90-day deadline:

You can apply for an extension, but you need a valid reason and CRA’s approval isn’t guaranteed. Your options for challenging the assessment become much more limited.

The pattern we see:

Business owner receives NOA in early May. Sets it aside. Discovers a problem in July when reviewing for other reasons. The 90-day objection period ended in early August. Now they’re scrambling to file an extension request or have lost the right to object entirely.

The Difference Between Notice of Assessment and Notice of Reassessment

Your initial NOA arrives a few weeks after filing. Sometimes, weeks or months later, another notice arrives: Notice of Reassessment.

What reassessment means:

CRA reviewed your return after the initial assessment and made additional changes.

What triggers reassessment:

You filed an amendment or adjustment request. CRA conducted a review or audit and found issues. CRA received additional information (late information slips, third-party reports) that changed your assessment. CRA corrected errors they made in the initial assessment.

Why this matters:

Reassessments can significantly change your tax situation—sometimes in your favor, often not.

A reassessment showing you owe additional tax means you now owe that amount plus interest from the original filing due date. The 90-day objection period starts fresh from the reassessment date.

The confusion:

Many business owners don’t distinguish between initial assessment and reassessment. They think “I already got my NOA, why is CRA sending another one?”

Understanding that reassessment means CRA made additional changes—and you have fresh objection rights—is critical.

What the Cryptic Codes and Notes Actually Mean

Notices of Assessment include codes, abbreviations, and notes that most business owners don’t understand.

Common codes:

Lines referenced by number (150, 236, 260, etc.) that correspond to specific tax form lines. Status codes indicating processing stage or issues. Benefit codes related to GST/HST credit, Canada Child Benefit, or other programs.

The problem:

These codes are meaningful to tax professionals and CRA staff but opaque to most business owners.

You might see a note that says “Review of line 236 pending” and have no idea what that means or what action (if any) you should take.

When codes matter:

Some codes indicate holds on your refund. Others indicate CRA is reviewing specific claims. Some trigger benefit recalculations or affect other programs.

Without understanding what the codes mean, you can’t assess whether there’s a problem that needs attention.

The Benefits and Credits Section Most People Ignore

Your NOA includes information about benefits you’re registered for and how your return affects them.

Common benefits tied to your tax return:

GST/HST credit. Canada Child Benefit (if you have children). Provincial benefits and credits. Income-tested programs where your reported income determines eligibility.

What can change:

If your reported income increased significantly, benefits might be reduced or eliminated for the coming year. If CRA adjusted your income on the NOA, that affects benefit calculations. If you’re newly eligible or no longer eligible for certain benefits based on this year’s return.

Why this matters:

You might be expecting to receive a certain benefit amount next year based on your filed return, but CRA’s adjusted assessment changes your eligibility.

Or you might discover you’re eligible for benefits you weren’t claiming.

Most business owners don’t review this section unless benefits are a significant part of their income. But even if benefits are small, changes can indicate other issues with your assessment.

When Everything Looks Fine But Isn’t

Sometimes your NOA appears correct at first glance. Refund matches expectations. Carry-forwards look reasonable. No obvious changes noted.

But problems can still exist:

CRA accepted information that’s actually wrong (they haven’t caught it yet). Carry-forward amounts are slightly off but not obviously wrong. Your return was processed correctly but wasn’t optimal strategically.

Example:

You claimed all eligible deductions. CRA accepted them. Your refund is what you expected. Everything seems fine.

But reviewing your overall tax situation reveals you could have structured things differently to pay less tax. Or you missed claiming certain credits that CRA didn’t flag because they can’t proactively identify what you’re eligible for.

The distinction:

An accurate NOA (CRA processed what you filed correctly) vs. an optimal tax outcome (you filed in the way that minimizes your tax within the rules).

Most business owners don’t have the expertise to know whether their tax situation is optimized even when their NOA is technically correct.

The Corporate Notice of Assessment Differences

If you’re incorporated, your corporate T2 return generates a separate Notice of Assessment with different information.

Corporate NOA shows:

Corporate tax owing or refund. Loss carry-forwards available. CCA schedules and remaining UCC balances. Investment tax credits. Refundable dividend tax on hand (RDTOH). Small business deduction limit.

Why corporate NOAs require different review:

The amounts and calculations are more complex. Errors in corporate NOA affect not just this year but future years’ planning. Some amounts (like RDTOH) affect how you take money out of the corporation.

The pattern we see:

Business owners focus on personal NOA and don’t carefully review corporate NOA. Or they see “nil balance owing” on corporate return and assume everything is fine without checking whether CRA made adjustments.

Corporate assessment errors can be particularly costly because they affect ongoing tax planning strategies.

Why “CRA Must Be Right” Is a Dangerous Assumption

Many business owners assume that if CRA issued an assessment, it must be correct.

The reality:

CRA makes errors. Information they receive from third parties can be wrong. Their automated systems sometimes misinterpret information. They make assumptions based on patterns that don’t apply to your specific situation.

When CRA errors happen:

They process information slips incorrectly. They apply payments to wrong tax years. They disallow legitimate deductions based on incomplete understanding. They miscalculate carry-forward amounts. They fail to apply credits you’re entitled to.

Why business owners don’t catch this:

They assume CRA has all the information and knows best. They don’t understand their return well enough to spot discrepancies. They’re intimidated by questioning CRA. They don’t want to draw attention to their file.

The cost:

Accepting incorrect assessments means paying more tax than you owe or losing carry-forwards you’re entitled to. These errors compound over multiple years if not corrected.

What Actually Warrants Objecting to Your Assessment

Not every discrepancy warrants filing an objection. The process has costs in time and professional fees.

When objection makes sense:

CRA disallowed significant deductions or credits incorrectly. Carry-forward amounts are wrong and materially affect future years. CRA’s changes result in substantial additional tax you don’t believe is correct. The assessment affects benefits or other programs significantly.

When objection might not be worth it:

Minor differences that don’t materially affect your tax. Changes where CRA is technically correct even though you disagree. Situations where the cost of objection exceeds the benefit. Cases where you don’t have documentation to support your position.

The judgment call:

This requires understanding CRA’s position, your position, the likelihood of success, and the cost-benefit of pursuing objection.

Most business owners don’t have the framework to make this assessment without professional guidance.

The Bottom Line

Your Notice of Assessment is more than a refund slip or tax bill. It’s CRA’s official record of your tax situation, your carry-forwards, and the baseline for future years.

Most business owners review it superficially—checking the bottom-line refund or owing and filing it away.

What they miss: changes CRA made, carry-forward amounts that might be wrong, benefit impacts, discrepancies that indicate problems, and the 90-day objection window.

Some missed issues are minor. Others compound over years, affecting future returns, benefits, and tax planning.

The difference between a cursory glance and a proper review often determines whether errors get caught and corrected or become permanent parts of your tax record.

Need Help Reviewing Your Notice of Assessment?

At KKCPA, we review Notices of Assessment for Ontario business owners to identify discrepancies, errors, and concerning adjustments.

We can help you:

Verify that CRA processed your return correctly
Identify changes CRA made and determine if they’re correct
Check carry-forward amounts against our records
Assess whether discrepancies warrant objection
File objections within the 90-day window if needed
Understand benefit impacts and other downstream effects

Don’t assume your Notice of Assessment is correct just because CRA issued it.

Contact KKCPA

📍 Serving Ontario businesses including Hamilton, Ancaster, Burlington, and the Greater Toronto Area
📞 Toll Free: 855-667-1727

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