During the voluntary period, a rule was established to reject an electronic house bill if the previous house bill was not on file. This was put in place to handle situations where not all freight forwarders involved in the consolidation were transmitting electronically. To ensure that all house bills were electronic during this period, it was decided that all house bills in all tiers had to be electronic, or the existing paper process would have to be used. However, when house bills become mandatory, the system will accept the tier 2 house bill even if the previous one is not yet on file, and a “not matched” response will be sent to the sender of the tier 2 house bill.