Ontario Mining Tax

Frequently Asked Questions

How do I register an account with the Ministry of Finance?

Before registering an account with the Ministry of Finance, you must first register with the Ontario Ministry of Government Services to obtain your Ontario Corporation Number (OCN). Once you have obtained your OCN, contact the Ministry of Finance at 1 866 ONT-TAXS (1 866 668-8297) or download the Request for Registration form [PDF - 576 KB].

When will my return be processed?

All returns will be processed as they are received.

When is my return due?

A completed return and any supporting documents must be filed within six months after the end of your taxation year.

When will I receive my assessment?

Assessments will be sent out after your return is processed. If you have an outstanding balance on your account you will receive a monthly statement.

When will I receive my refund?

If you are entitled to a refund, it will be paid after the assessment is issued.

Will I be charged interest and/or penalty for the period until my return is processed?

If you have done the following on time: made your instalment payments, paid the balance of tax in full, and filed your return, you will not be assessed interest or penalty for the delay in processing your return.

I received a statement with an estimated amount owing. How was the amount calculated?

Tax clients who do not file their returns on time may receive an assessment that has automatically estimated an amount of tax owing. Estimated amounts will be calculated based on the average of total tax due up to the past six (6) filed tax returns excluding nil and credit returns.

Where can I mail/deliver my return?

Mail or deliver to:

Ministry of Finance
33 King Street West
PO Box 620
Oshawa ON L1H 8E9

Tax returns and payments will be accepted at certain ServiceOntario locations or call 1 866 ONT-TAXS (1 866 668-8297).


File online using ONT-TAXS online – the ministry's secure and convenient online tax service available 24 hours a day, seven days a week.

How do I make payments for my Mining Tax instalments and balance of tax due?

Payments can be made using any of the following methods:

Payments should be in Canadian funds and be made payable to the Minister of Finance. Your Identification Number should be printed on the back of the cheque or money order.

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