Skip to main content
Book a free consultation

Personal tax

Why you owe tax this year and what to do about it

Owing tax when you expected a refund is common, and it rarely means you did something wrong. A balance owing appears when the tax calculated on your whole-year income is more than the tax already paid for you or by you. This article explains the arithmetic, the situations that usually cause a shortfall, what the CRA charges if the balance is not paid on time, and how to adjust before next year. It is written for Ontario employees, self-employed people and owner-managers.

Sora Accounting & Tax · General information · Editorial policy
Updated · 5 min read

Tax payable weighed against tax already paid

A balance showing total tax payable on one side and tax withheld plus instalments on the other, with the difference as the balance owing.

Visual labels: Total payable; Tax withheld; Instalments paid; Balance owing.

See the sourced 2026 Ontario tax guide: rates, limits and deadlines →

What to take away

  • A balance owing is total payable minus total credits; it grows when withholding was too low for your real income.
  • Interest runs daily from the day after the due date, so pay what you can by April 30 and file on time even if you cannot pay in full.
  • Fix the cause: update your TD1 forms, review instalments, or plan for withdrawals and extra income before the year ends.

How the CRA gets to a balance owing

Your return works out your total payable, which is your net federal and provincial tax plus certain other amounts, and subtracts your total credits, which include tax deducted from your pay and any instalments you paid. If the result is positive you owe the difference. If it is negative you receive a refund. The notice of assessment shows the result as a balance owing, a refund or a zero balance.

Illustrative numbers: if your total payable is $9,000 and $8,200 was withheld during the year, your balance owing is $800. Nothing in that calculation is a penalty. It is simply tax on income that was not fully covered at the time you were paid.

Common reasons people owe

The CRA’s own example is an employee who did not have enough tax deducted from their pay. This can happen when you work for more than one employer, since each payroll calculates withholding from the pay it handles. The CRA’s instalment guidance lists other typical causes: self-employment, rental or investment income, certain pension payments and income from more than one job, none of which usually has enough tax taken off.

Other triggers include a deduction that has ended, such as child care you no longer pay for, and a province of employment that differs from your province of residence. CPP contributions on self-employment earnings also add to what you owe. Our article on setting aside tax when self-employed covers that case in more detail.

RRSP withdrawals, benefits and other surprises

When you withdraw from an RRSP, the financial institution withholds tax at 10% on amounts up to $5,000, 20% on amounts over $5,000 up to $15,000 and 30% above $15,000 for residents outside Quebec. The CRA notes that this may not equal the tax you owe at your own rate, so the withdrawal is added to your income and you may owe more.

Employment insurance and some other benefits are reported as income, and you may also have to repay part of certain social benefits, such as EI or old age security, if your net income is above the threshold for the year. That repayment is added to your total payable. If you received a T4E, T4A or similar slip, check what tax was withheld before assuming the amount was final.

What to do right away

File by the due date even if you cannot pay. For most individuals the due date is April 30 following the tax year, so for 2026 returns that is April 30, 2027. If you or your spouse or common-law partner are self-employed, the filing date is generally June 15, 2027, but any balance is still payable by April 30. The CRA reminds filers to pay before the deadline to avoid interest.

Check the return for errors that inflate the balance, such as a missed slip, an unclaimed credit or a carryforward you did not use. Do not rush to reduce the balance by guessing at deductions, since an unsupported claim can create a larger problem on review. If the notice of assessment looks wrong, our article on disputing an assessment explains the next steps.

Interest and penalties if you pay late

The CRA charges compound daily interest on an unpaid balance starting the day after the due date, and the rate can change every three months. If the due date falls on a weekend or holiday, a payment received on the next business day is on time.

Filing late when you owe tax carries a penalty of 5% of the balance owing plus 1% for each full month late, up to 12 months, and the penalty is higher if you were penalized in the previous three years and received a demand to file. If you miss instalments, instalment interest may apply, and a penalty is applied only if that interest is more than $1,000. The CRA may cancel interest or penalties where circumstances beyond your control prevented compliance.

How to pay, or arrange to pay over time

The fastest way is usually online banking, where you add the CRA as a payee and use the option that matches your account, and you get a confirmation number. Allow processing time, because the CRA looks at when the payment is received. Other options include a cheque or debit with a remittance voucher and cash or debit at a Canada Post outlet with a QR code, for a fee. The CRA will not accept bitcoin, gift cards or cash as payment, and a request for them is a scam.

If you cannot pay in full, contact the CRA early. It offers payment arrangements, and its Manage balance service in My Account lets individuals with personal income tax debts of $1,000 or more set one up without speaking to a collections officer. Interest keeps accruing while you pay. Our guide on catching up on taxes covers what to do if you are behind on filing as well.

Prevent it next year

If you owe because of too little withholding, update your TD1 forms with each employer so deductions better match your total income. The CRA notes that employees may increase withholding by filing revised TD1 forms, which is useful if you hold several jobs.

If you have self-employment, rental or investment income, you may need to pay tax by instalments. For 2026, you generally must pay them if your net tax owing is more than $3,000 in 2026 and in either 2025 or 2024. Read our article on instalments for the test and due dates, and plan for RRSP withdrawals and extra income before the year ends, not after.

What to bring to an accountant

Bring your last two notices of assessment, this year’s slips, a list of income that had no slip, your TD1 forms and your year-to-date pay stubs. Ask how much tax is likely to be owed for the year, whether instalments are needed and whether a change in withholding would help.

If you already owe from past years, bring every CRA letter. An accountant can confirm your balance, advise on payment arrangement options and prepare any outstanding returns so the problem does not grow.

Sources & editorial notes

Sources checked October 24, 2026. The examples are illustrative and provide general information. Discuss how the guidance applies to your circumstances with your accountant.

Rules and guidance can change. Use the current official source and confirm the treatment for your facts. To flag an error, contact Sora.