CRA (the Canadian income tax department) has the right to serve third party demands, without a court order, on debtors or potential debtors of a taxpayer who owes money to CRA. If you receive such a third party demand you must make payments directly to CRA, and not to your creditor.
"This article provides information of a general nature only. It is only current at the posting date. It is not updated and it may no longer be current. It does not provide legal advice nor can it or should it be relied upon. All tax situations are specific to their facts and will differ from the situations in the articles. If you have specific legal questions you should consult a lawyer."