The integration tax: what five suppliers really cost

There's a number that never appears in any supplier's proposal: the cost of making their work coexist with everyone else's. Call it the integration tax. You pay it in coordination hours, in things falling between remits, and in the phrase 'that's not really our side'.

How the tax compounds

Connections grow faster than components. Two suppliers share one interface; five suppliers share ten. Every interface needs someone who understands both sides — and that someone, by default, is you. It's why adding a 'small' email project to a website project so often doubles the friction rather than adding a little.

• n suppliers ⇒ n(n−1)/2 relationships that can misfire
• Every boundary is a place where accountability can hide
• Each supplier optimises their fragment, nobody optimises the system
• Institutional knowledge fragments — no one can answer 'how does it all work?'

Paying it down

Sometimes multiple suppliers are right — genuine specialisms exist. But default to fewer interfaces: consolidate around one accountable partner for the digital system, and let true specialists plug into a structure someone owns. The test of a good setup is a boring one: when something breaks at the seam, is it obvious whose job it is?