CBP (US Customs) determines based on the past 12 months of duties, taxes and fees that the current bond limit is no longer adequate. CBP (US Customs) then sends a letter of insufficiency to the importer per the address in the database and usually a copy to the surety. Usually, US Customs allows time to rectify the situation.
Once the letter has been sent, the importer has three options:
If no action is taken, then 15 days after the date of the letter, the current bond would be placed into insufficient status. The bond would remain, but no entries would be allowed under the bond.
If within 15 days of the date of the letter, the surety submits a termination request to be effective no later than 30 days after the date of the letter. This would allow the bond to be sufficient until the bond is terminated.
Any surety can submit a bond with the minimum bond limit required in the letter to be active after the termination date of the current bond.
As a reminder, the amount in the letter is the minimum required amount CBP will accept. The importer should be forecasting their next 12 months of import activity to determine if they need a bond limit higher than the amount given by CBP.