Normally, if an importer fails to declare goods or undervalues the goods, the Canada Border Services Agency (CBSA) may seize goods as forefeit and/or ascertain an amount as a penalty to get the goods back. An ascertained forfeiture occurs when the goods cannot actually be seized (because the good cannot be located or seizing the good is impracticable). It is a civil proceeding (as opposed to a criminal proceeding) that is set out in section 124 of the Custom Act (Canada).
What normally occurs is the CBSA sends a Notice of Ascertained Forfeiture by registered mail or hand deliver it to your door. The Notice of Ascertained Forfeiture will indicate the amount of money that is payable by the Recipient of the Notice. Usually the amount in the Notice of Ascertained Forfeiture is high enough that the recipient will take notice.
If the person against whom the ascertained forfeiture is made wishes to file an appeal, they may request the Minister make a redetermination within 30 days of receiving the Notice of Ascertained Forfeiture. The person is required to provide all the relevant information (to overturn or reduce the amount of the ascertained forfeiture) in the request for a redetermination.
In my experience, the CBSA has issued notices of ascertained forfeiture in cases where they believe a person has been smuggling goods into Canada. The belief may be based on information provided by USCBP or another foreign government or an informant (or a former/disgruntled business associate/spouse). For example, the CBSA has issued Notices of Ascertained Forfeiture in respect of tobacco, vehicles and other alleged undeclared goods that are transported at non-border points. The belief that undeclared goods have been imported into Canada may also be based on the x-ray of a box containing the receipts for an expensive watch/piece of jewelry.
Since an ascertained forfeiture is an extraordinary action taken pursuant to a statutory provision, all the preconditions set out in the law must be satisfied. The CBSA cannot issue a Notice of Ascertained Forfeiture because it is more convenient. If the goods are subsequently seized, the ascertained forfeiture should be cancelled. If you receive a Notice of Ascertained Forfeiture, consider contacting a lawyer because a criminal smuggling charge may also be in your future.