This would be the case if it were true, but it isn't. CDS is highly integrated with all of HMRC's systems. Moreso than almost anything else in the place actually.
"Integration" in this case is more of a contractual term that may be better read as "delivery" or "build" - it simply implies another layer of components and procurement underneath the prime "integration" contract. Some will be custom, some will be cots, some will be glue. The contract is to run those subcontracts, pull it all together and deliver it.
The problem with CDS is that back when it was specced in 2013 Brexit wasn't even a word, so it was very much defined with the rest of the world in mind. Then of course it suddenly needed to handle something like 100x more submissions of about 10,000x more varieties, from a set of companies that were barely even in the hierarchy for the backing datastore. And it needed to do that in the space of two to three years. This happened within touching distance of the originally-designed CDS being delivered, and within months of the originally-planned decommissioning of CHIEF (the previous system). So just about the worst case scenario.
The fact this has only cost an eight figure sum and six years to tidy up is a miracle.
Biting the hand that feeds IT
