When one parent travels with a child, even if the parents are not separated, it is always good practice to have a travel consent letter. A travel consent letter provides consent from the parent(s) or guardian(s) not with the child to travel abroad, sets out the details of travel, whether the child is traveling alone or with only one parent/guardian, and contact information for the non-traveling parent/guardian.
While a travel consent letter is not a legal requirement for traveling with a child without one or both parents, it may be requested during travel. Immigration authorities may ask for a travel letter when entering or leaving a foreign country or Canadian officials may ask the for a letter when re-entering Canada.
The letter can be witnessed by anyone who is over the age of majority or by a notary public. The Government of Canada strongly recommends that the letter be witnessed by a notary public so that border officials will be less likely to question its authenticity. When a document is notarized it adds the further check that someone appointed by the province of Ontario to be a notary public has confirmed the identity of the person signing the document. All lawyers who are members of the Law Society of Ontario can be appointed as a notary public (and majority, if not all, have applied to be a notary public). Non-lawyers may also apply for appointment as a notary public if they are a Canadian citizen and under specific employment conditions.
The Government of Canada has more information and sample consent letters on its website: https://travel.gc.ca/travelling/children/consent-letter.
Before traveling out of the province or country, ensure that your court order(s) permits the child to travel. In some cases, the court may order the child not be removed from Ontario or Canada.