Ontario Tax Season Prep: What You Need to Know

Ontario tax season basics: deadlines, rules, and what changes

Tax season can feel mysterious because it blends everyday life with a system that has real consequences: your refund, your benefits, your ability to borrow, and whether you get a letter from the CRA. In Ontario, you file one personal return (the T1) and it covers both federal and Ontario provincial income tax. You do not file a separate Ontario return, but Ontario specific credits and surtaxes are calculated inside the same T1.

A practical way to think about tax season is this: you are reconciling what you earned and paid during the year with what you should have paid under Canada's tax rules. If you paid more through payroll deductions, you may get a refund. If you paid too little, you may owe a balance. The CRA also uses your return to calculate benefit payments like the GST/HST credit and the Canada Child Benefit (CCB). That is why filing on time matters even if you had low income or no tax owing.

Key deadlines change slightly each year, but the structure is stable. For most Canadians, the filing deadline is April 30. If you or your spouse or common law partner are self-employed, the filing deadline is typically June 15, but any balance owing is still due by April 30 to avoid interest. The CRA posts the current year deadlines and filing guidance on the CRA personal income tax page.

Ontario households also feel tax season through costs that show up outside the return itself, such as interest rates and borrowing costs. The Bank of Canada rate environment influences mortgage and HELOC interest, which can affect decisions like whether to contribute to an RRSP or pay down high-interest debt first. A good tax plan is not just about credits, it is also about timing and cash flow.

To keep this guide actionable, the rest of the article follows a time-based roadmap. You can complete most of the high-impact prep in about 60 days, even if you are starting from scratch.

Days 1 to 7: Get organized (CRA access, slips, and a clean paper trail)

Your first week is about removing friction. Most tax season stress comes from missing documents, locked CRA accounts, and last-minute guessing. If you do nothing else, do these three things: confirm access to CRA My Account, build a checklist of slips, and create a simple folder system for receipts.

Start with CRA My Account because it is the hub for your tax life in Canada. You can view your Notice of Assessment, RRSP deduction limits, carryforward amounts, and many slips that financial institutions submit to the CRA. The CRA explains sign-in options and security steps on the CRA My Account overview. If you have not logged in recently, do it now, not in late April when call queues get long.

Next, list the slips you expect. In Ontario, common slips include T4 (employment), T4A (pensions, scholarships, some contract income), T5 (investment income), T3 (trust income), and T2202 (tuition). If you sold investments in a non-registered account, you may also need a T5008 or a broker gain and loss report. For many people, the biggest time sink is not the tax software, it is hunting down a missing T5 or forgetting a small investment account.

Then build a paper trail that matches how CRA reviews work. CRA typically asks for support after filing, not before. That means you should be ready to prove claims like medical expenses, childcare, and donations. A simple system works:

• Create one folder labeled by tax year (digital or physical).
• Inside it, keep subfolders: Income slips, Deductions, Credits, Medical, Donations, Childcare, Moving, Work from home, Rental (if any).
• Save receipts as you get them, then keep a one-page summary list of what each receipt supports.

Finally, check last year's Notice of Assessment. It tells you what the CRA accepted, what it adjusted, and what carryforwards you have. Carryforwards commonly include tuition amounts, capital losses, and donation credits. Many Canadians miss money simply because they do not know they have amounts available.

Days 8 to 21: Maximize deductions (RRSPs, childcare, moving, WFH)

Once you are organized, shift to deductions. A deduction reduces taxable income, which can lower the tax you owe. Credits work differently, they reduce tax payable after income is calculated. Ontario residents benefit from both federal and Ontario calculations, so a deduction can have a double impact.

Start with RRSP contributions because they are one of the biggest levers for middle-income households. RRSP contributions can reduce taxable income and potentially increase income-tested benefits. The CRA explains RRSP rules and limits on the CRA RRSP information page. Your personal RRSP deduction limit is on your Notice of Assessment and in CRA My Account. A common misconception is that contributing is the same as deducting. You can contribute and carry the deduction forward, which can be useful if your income is unusually low this year.

If you are trying to decide between RRSP and TFSA, remember the tax season context: RRSPs help most when your marginal tax rate is higher today than it will be when you withdraw. TFSAs do not give a deduction, but withdrawals are tax-free and do not reduce income-tested benefits. Many Canadian banks publish plain-language comparisons, such as RBC's RRSP vs TFSA overview. Use those comparisons, but anchor the decision to your cash flow and your likely tax bracket.

Next, review childcare expenses. Childcare is often one of the largest deductible costs for Ontario families, and it is frequently misclaimed. Generally, the lower-income spouse or partner claims the childcare deduction, with specific exceptions. The CRA outlines eligible childcare expenses and limits on the CRA childcare expenses page. If you used a daycare, after-school program, or day camp, make sure you have receipts with the provider's details.

Then consider moving expenses. If you moved for work or school and your move brought you at least 40 km closer to the new location, you may be able to claim eligible moving expenses. Ontario renters and new homeowners often miss this after relocating within the province for a job change. The CRA explains the rules on the CRA moving expenses page.

Finally, address work-from-home claims. The temporary flat-rate method that existed during earlier pandemic years changed, and many Canadians now need to use detailed methods with T2200 or T2200S forms if eligible. Requirements depend on your employment arrangement, and CRA guidance is the best source. See the CRA's work-from-home expenses guidance.

Days 22 to 35: Claim Ontario credits and benefits (and protect your payments)

This phase is about credits and benefits, which are where many Ontario households leave money on the table. Credits reduce tax payable, and benefits are payments the CRA calculates based on your family net income. Filing accurately and on time is what protects these payments.

Start with the GST/HST credit and the Ontario Trillium Benefit (OTB). The OTB combines three credits: the Ontario Energy and Property Tax Credit, the Ontario Sales Tax Credit, and the Northern Ontario Energy Credit (for eligible residents). The CRA administers these payments, and eligibility depends on factors like age, income, rent paid, property tax, and where you live. Ontario-specific information is summarized on the Government of Ontario tax credits and benefits page.

If you rent in Ontario, pay close attention to rent amounts and addresses because they can affect OTB calculations. Keep rent receipts or a rent ledger, and confirm your landlord's details. If you own, keep your property tax bill. These are the kinds of documents CRA may ask for later.

For families, the Canada Child Benefit is often the largest monthly benefit. It is recalculated every year based on your net family income and your marital status. If you delay filing, you can delay or interrupt payments. The CRA explains eligibility and how payments are calculated on the CRA Canada Child Benefit page. Even if your income is low and you owe no tax, filing is still how you keep benefits flowing.

If you are a student or recent graduate in Ontario, review tuition amounts and interest on student loans. Federal student loan interest is not currently claimable as a non-refundable credit under current rules, but tuition carryforwards can be valuable. Make sure your T2202 is correct and that any unused tuition amounts are tracked. Many people assume unused tuition disappears, but it can carry forward.

Also consider medical expenses and donations. Medical expenses are claimed as a credit, and the optimal strategy often involves grouping expenses into a 12-month period that maximizes the claim. Donations can also be more valuable when bundled into one year because the credit rate increases after the first threshold. The CRA's charitable donations guidance is a good reference for eligible receipts and limits.

Days 36 to 45: Choose how to file in Ontario (software vs accountant vs free clinics)

Now you are ready to file, but how you file matters. In Canada, most people file electronically using certified tax software, a tax professional, or a free community clinic if eligible. The best choice depends on complexity, time, and your comfort with recordkeeping.

If your tax situation is straightforward, software can be efficient. The CRA publishes a list of certified options through its NETFILE program on the CRA NETFILE page. Many platforms can import slips directly from CRA Auto-fill my return, which reduces data entry errors. The tradeoff is that you still need to understand what you are claiming and keep receipts.

If you have self-employment income, rental income, significant investments, or a major life change (marriage, separation, death in the family, new home purchase, moving across provinces), an accountant can be worth it. A professional can also help with tax planning, not just filing. Ask specifically about experience with Ontario credits and CRA review support. Fees vary widely, and the cheapest option is not always the best if you are exposed to reassessments.

If you are low-income or have a simple tax situation, free tax clinics can help. The CRA supports the Community Volunteer Income Tax Program (CVITP). Eligibility is based on income and complexity, and availability varies by location. Learn more on the CRA free tax clinics page.

Regardless of filing method, make a final pre-filing checklist:

1. Confirm your name, address, date of birth, and SIN are correct.
2. Confirm marital status and the effective date of any change.
3. Reconcile employment income to your final pay stub.
4. Ensure you captured all investment slips, including small bank accounts.
5. Confirm RRSP contributions are reported in the correct window.
6. Double-check rent or property tax amounts if claiming OTB.

Finally, decide how you will receive your refund or pay your balance. Direct deposit is faster and reduces the risk of lost cheques. The CRA explains how to set up direct deposit on the CRA direct deposit page.

Days 46 to 60: Avoid the most expensive mistakes (and CRA review triggers)

This stage is quality control. Many tax season problems are not fraud, they are mismatches and omissions. The CRA receives slips directly from employers and banks, so if you forget a T5 or T4A, the CRA can reassess later. That can mean tax owing plus interest, and sometimes penalties.

A common mistake is misunderstanding what counts as self-employment income. Side gigs, contract work, and online sales can create taxable income even if you did not receive a slip. If you earned income, you generally need to report it. The CRA's guidance on self-employment is detailed and worth reading if this applies to you, starting from the CRA self-employed page.

Another common issue is claiming work-from-home expenses without the right support. If you are using the detailed method, you may need an employer form and you should keep a clear calculation of workspace percentage and eligible expenses. Guessing is risky because CRA review programs often request documentation.

Watch for errors in capital gains reporting. If you sold stocks or ETFs in a non-registered account, the taxable amount depends on your adjusted cost base (ACB), not just what the T5008 shows. Many broker slips can be incomplete for ACB. If you are unsure, consult your brokerage reports or a tax professional. Canadian banks and brokerages often publish investor tax guides, for example TD Direct Investing's resources, but always cross-check with CRA rules.

Finally, do not ignore a balance owing. The CRA charges interest on late payments, and interest rates can change quarterly. Even if you cannot pay in full, filing on time and setting up a payment arrangement is usually better than delaying. The CRA explains payment options on the CRA pay your taxes page.

After you file: refunds, balances owing, instalments, and CRA follow-ups

After filing, your job is not over. This is when you receive your Notice of Assessment, confirm your refund or balance, and adjust your plan for next year. If you treat this step as part of a system, tax season gets easier every year.

First, read your Notice of Assessment carefully. It confirms the CRA's assessment of your return, your RRSP deduction limit for the next year, and any carryforwards. If the CRA changed something, it will show. You can access it through CRA My Account. If you disagree with an assessment, there are formal dispute steps, but start by understanding whether it was a slip mismatch, a missing receipt, or a calculation difference.

If you are getting a refund, decide where it goes before it arrives. A refund is not free money, it is often the result of over-withholding or credits. Consider using it to:

• Pay down high-interest credit card debt (often 20% APR or more at many Canadian issuers)
• Build an emergency fund in a high-interest savings account
• Top up an RRSP or TFSA for next year planning
• Prepay an upcoming expense like property taxes or insurance

If you owe money, pay as soon as possible and consider adjusting payroll withholdings if you consistently owe each year. Employees can review TD1 forms, and self-employed individuals may need to plan instalments. The CRA explains instalment requirements and reminders on the CRA instalments page.

If you receive a CRA review letter, respond by the deadline and provide exactly what is requested. Do not send extra unrelated documents. Keep copies of what you submit. If you used tax software, many products store a PDF of your return and schedules, which helps you match the CRA's request to what you claimed.

Finally, turn your tax season learning into a year-round habit. Set a monthly reminder to save receipts, track donation totals, and keep a simple log of medical and childcare payments. If you are self-employed, set aside a percentage of each payment for taxes and HST/GST if applicable. This reduces the emotional shock of a big April bill.

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