Lay-by shoppers may be unaware of the risks they currently face, assuming the law provides protection it does not, Consumer Affairs Minister Chris Tremain says.
Under current laws, there is no requirement for a formal agreement for lay-by sales, and there are several holes that could leave buyers with shoddy products.
However, the gaps in the law are being plugged by new legislation, which aims to update and merge a number of old consumer-based laws, and spell out the obligations of buyers and sellers.
The Consumer Law Reform Bill passed its first reading in Parliament last week, and will now be considered by the commerce select committee.
Under the bill, a written agreement would be required to clarify the terms of lay-by sales.