The aggregation rule in public procurement
If a contracting authority enters into multiple contracts to fulfil a single requirement, the value of those contracts should, under the Public Contracts Regulations 2006, be aggregated to decide whether the purchase is above the threshold.
The Regulations explicitly say that a contracting authority should not enter into separate contracts or exercise a choice under a valuation method with the intention of avoiding the application of the Regulations.
The effect of the aggregation rule is that if there are lots of separate contracts for the same type of goods/services/works which in the aggregate exceed the relevant threshold then those individual contracts still need to be advertised even though individually they are below the threshold.
When assessing the point ask yourself this question: If the Regulations did not exist would I have procured the goods/services/works under just one contract?