On the Transactions tab under a Household record, you will see a green “Add” button. This button will allow you to add Transactions to members within the Household, but you are unable to physically assign a gift to the Household itself. The default will be the Head of Household, but you can change it to any other Constituent. If the gift is added to a member of the Household, you will then be able to see it on the Transactions tab within that Household’s record.