Can my ex deny my vacation with my kids?

The typical approach in these types of situations is to seek out express written consent from the non-travelling spouse. Sometimes a court order or separation agreement will indicate and give some guidance as to the non-travelling spouse signing a travel consent form. However, if the travelling spouse will be incurring expense for the trips including flight costs, accomodation charges, etc., then it is better to ensure that there will not be any issues at the border. A consultation with a family law lawyer would be helpful to formulate a plan and approach to address the issues. It may be necessary to bring a motion before a court to seek a court order permitting the travel with the children, and if so granted then the party could always respectfully ask the court to make a costs order in favour of that party in hopes to be reimbursed some of the expenses that were incurred with the lawyer. The ages of the children are obviously a significant factor, as are providing clear details of the planned vacation. The simple reality is that the border may request a copy of the court order and if the parents have joint custody then there may be a need to present a written signed travel consent or court order permitting the travel.