In a buy-and-build, synergy quickly becomes a number in a memo: an amount per platform, added up to a total that makes the deal more attractive. The problem does not lie in the adding up, but in what lies beneath that number. A synergy amount without an assumption, without an owner and without a measuring point is not substantiation. It is an expectation that someone once wrote down.
Every synergy rests on an assumption about the reality after the deal: that two purchasing departments can be merged, that a back office will be set up once, that customers of platform A will also accept platform B. That assumption is rarely made explicit, while that is precisely where the vulnerability lies. If you want to know how to look at which assumption underlies your synergy amount in a buy-and-build, that is the starting point before a single euro is recorded. A synergy that cannot be traced in one sentence, with an assumption, to an operational change, is a gamble with a price tag.
This is also the moment to ask the question that is often skipped in a buy-and-build: should this part actually be combined? Two platforms can exist side by side without shared synergy, and that is sometimes the better outcome than a forced integration that costs time and attention without the assumption holding true.
An amount on a line in a spreadsheet delivers nothing if no one is responsible for making it land. Synergies that are assigned to "the integration team", rather than to a name with an agenda and a mandate, usually disappear quietly by the end of the year. Anyone wondering who is the owner of a synergy in a buy-and-build is actually asking who will be held accountable if the amount does not land. Without that answer, the synergy is a wish, not a plan.
The owner is not automatically the CFO who approved the amount, nor automatically the operations director of the acquired platform. It is the person who can carry through the operational change behind the assumption, and who is held to account for that at a fixed moment, not only at the year-end close.
The world in which the synergy was calculated changes as soon as the deal is signed. Customers react differently than expected, a system migration takes longer, a key figure leaves. A synergy amount that seemed achievable at signing can be outdated three months later — in either direction. To determine how to test whether a synergy is still achievable in a buy-and-build, a fixed testing moment is needed, linked to the assumption laid down at the start. Without that reference point, every discussion about achievability becomes a feeling rather than a comparison.
Tracking synergies works best when it is visible and simple, not hidden in an extensive report that no one opens in the meantime. One way to do this is how do you track synergies with traffic lights in a buy-and-build: a status per synergy that shows at a glance whether the assumption still holds, is wavering, or has already been dropped. This does not replace a substantive assessment, but it prevents a synergy from silently disappearing without anyone noticing.
Not every synergy achieves the amount with which it entered the deal, and that in itself is not a failure — it becomes a problem only when nothing is done about it. The question what do you do with a synergy that does not land in a buy-and-build concerns that next step: adjusting, reallocating to another part, or acknowledging that the assumption was never correct. Without that step, a vanished synergy remains unnoticed in the overall picture, and it distorts every report that follows.
This is directly connected to the reason the deal was made in the first place. A synergy amount that has become disconnected from what is a deal thesis and why does it disappear is a number without an anchor point. The synergy baseline, the Day 1 plan and the Day 100 plan are three generators that lay down this structure: the assumption, the owner, the testing moment, and the place where a synergy that does not land is recorded rather than omitted.
This page describes the structure that should underlie a synergy amount. The tool that delivers these generators and the integration office is under construction; anyone who wants to use this as soon as it becomes available can join the waiting list.
Tracking synergies, tracing assumptions and flagging deviations is, in part, repetitive work: gathering data, updating statuses, marking deviations. For teams wondering how much of that work can be done without people, the werkscan from FTE TO AI calculates per task which part of the work can be taken over by AI, so that synergy monitoring depends less on who happens to have time to update the spreadsheet.
Vraag maar wat er op Day 1 moet staan, of wat integreren juist kapotmaakt.
Answers come from this site’s knowledge base. Not tailored advice, and not a scan of your company.