The agency changed the requirements after we submitted, is that allowed?

Agencies can amend tender documents, but they must do so fairly and transparently. Under the Government Procurement Rules, changes should be communicated to all participants at the same time, allow sufficient time for suppliers to respond and not disadvantage or favour any supplier. If the change is material, the agency should extend the deadline. You can ask for an extension and for clarification about how the changes will be applied. If the process ends up being unfair, such as where changes were made to favour a particular bidder after seeing bids, you may complain to the agency and to the Ombudsman, and in extreme cases seek judicial review. Keep your records of costs and all correspondence, since agencies are not usually liable to reimburse bid costs unless the terms provide for it.