Inputs
The over-contribution amount that stayed in the account
Whole months the excess remained (e.g. 3 for three full months)
Estimate CRA TFSA over-contribution tax (penalty) based on your available room, contributions, and withdrawals over a date range.
The penalty is 1% per month on the highest excess amount in each calendar month. This tool models that rule so you can see how excess and penalties change over time.
No opinions. No hidden assumptions. Just arithmetic.
Quick estimate for one excess amount over a known number of months.
This simplified estimate assumes the excess amount stayed the same for the full number of months entered.
This is a simplified estimate for a constant excess amount. If your excess changed over time, use Advanced mode.
CRA charges 1% per month on the highest excess amount in each calendar month. The penalty is the sum of those monthly amounts. This calculator estimates that total.
The simple mode assumes the excess amount stayed the same for the full number of months you enter. If your excess changed over time, use Advanced mode.
Use Advanced mode when contributions, withdrawals, or room changes happened on different dates and you want a month-by-month estimate based on the highest excess in each month.
In real life, withdrawals add to your contribution room starting January 1 of the next year, not in the same year. This calculator’s Advanced mode models that: withdrawals reduce excess from that point forward but do not restore same-year contribution room.
Disclaimer: All content on The Long Math — including articles, essays, calculators, tools, or any other material — is provided solely for educational and informational purposes and does not constitute financial, tax, legal, or investment advice. Any results or projections are based on simplified models, assumptions, and user-supplied inputs and may not reflect real-world outcomes. You are responsible for evaluating the accuracy and applicability of the information provided and for conducting your own due diligence. Before making financial decisions, consult a qualified professional.