Before government tenders in Wales are advertised the buyer defines the contract type.

There are different types of contract used in public sector procurement. These include:

• One-off purchases – Used for short-term agreements to supply goods and services to meet an individual requirement.

• Call-off contracts – Used for supplying a specific quantity of goods or services over a given time period. Delivery is either made via a delivery schedule or by separate 'call-off' orders placed against the contract.

• Framework agreement – Used when buyers call upon services or goods from a number of suppliers without the need to use a tender process each time. Framework contracts are often used for consultancy services.

• Term contracts – Used for contracts that operate over a specified period of time.

• Sub-contracting – Used for suppliers that will delegate part of a contract to another contractor, as many of the higher-value government contracts go to large companies.