The buy-and-build model has a simple appeal. Buy a platform at one multiple, add smaller companies at lower multiples, integrate them, and exit the combined business at a higher multiple than any of the pieces cost. On a spreadsheet, every add-on is accretive the moment it closes.

In practice, a large share of the value in a roll-up is won or lost in how add-ons are screened, and a surprising number of platforms end up paying for their bolt-ons twice: once at closing, and again in the integration cost, management distraction, and customer attrition that the screening process never priced. The multiple on the LOI is the visible price. The rest arrives over the following eighteen months.

Why add-on screening is different from platform screening

A platform acquisition is evaluated mostly on its own merits: quality of earnings, market position, management. An add-on should be evaluated almost entirely on its fit with the platform, because the add-on will not be run as a standalone business. That changes which questions matter. A small company with a weak finance function and a founder who wants to leave might be a poor platform and a perfectly good add-on. A strong, independent business with its own culture and systems might be exactly the opposite.

The screening criteria should reflect that. Before any names go on the list, the platform should write down what an add-on is supposed to contribute: new geography, new customers for existing products, a product the platform's customers already want, technical capability, or simply scale. An add-on that does not clearly contribute one of those is a second, smaller platform, and the plan was not to own two.

The four costs the LOI multiple does not show

1. Integration cost. Every add-on needs its finance, payroll, systems, and reporting folded into the platform. In software, that can also mean migrating customers from one product to another or supporting two codebases indefinitely. Estimate the one-time cost of integration and the run-rate cost of anything you decide not to integrate, and add both to the effective purchase price.

2. Customer attrition on integration. Customers who chose a small vendor sometimes chose it precisely because it was small. A change of ownership, a new support team, a forced product migration, or a price increase can each trigger churn. The screening question is how many of the add-on's customers are there because of the founder or the local relationship, and what happens to them when that changes.

3. Management bandwidth. Integrating a company takes the time of the platform's best people. A platform attempting three add-ons in a year while also delivering its own growth plan will usually do at least one of those things poorly. That opportunity cost is real, even if it never appears in a model.

4. Key-person dependency. Small add-ons frequently depend on the founder for sales, customer relationships, or technical knowledge. If the founder leaves at close, or after a short transition, the platform may find it has bought a customer list rather than a business. Retention arrangements help, but they need to be sized to the dependency, not added as an afterthought.

A screening framework that prices fit

A simple scoring approach works better than intuition, because it forces the same questions to be asked of every candidate. For each target, score from one to five on:

  • Strategic contribution: how directly the add-on delivers the stated purpose (geography, product, customers, capability).
  • Customer overlap and cross-sell: whether the add-on's customers can realistically buy the platform's products, and vice versa, based on segment and buyer persona rather than hope.
  • Integration complexity: systems, product architecture, pricing model, and contract structure compared to the platform.
  • Founder and team dependency: how much of revenue and operations rely on individuals who may not stay.
  • Cultural and operating fit: how the business actually runs day to day, including sales motion, service standards, and decision making.

Then compute an effective multiple: purchase price plus estimated integration cost plus a probability-weighted allowance for customer attrition, divided by the EBITDA you expect the add-on to contribute after integration, not before. Ranking candidates on effective multiple rather than headline multiple often reorders the list, and it is usually the cheap, complex, founder-dependent targets that fall furthest.

Sequence matters

The first add-on after a platform acquisition sets the integration playbook for everything that follows. It is usually worth choosing a first add-on that is simple to integrate, even if it is not the most strategically exciting, because the platform learns how to integrate on an easier case. Complex, high-value targets are better attempted once the finance function, systems, and integration team have been proven.

Timing also matters for the exit story. Buyers at exit will look at how acquired revenue has performed since each deal closed. A portfolio of add-ons that retained their customers and grew inside the platform supports a higher exit multiple. A portfolio that shows acquired revenue shrinking every year tells a buyer that the growth was purchased, not built, and they will price it that way.

Build the pipeline before you need it

Finally, add-on screening works best when it starts before the platform closes. A mapped universe of potential bolt-ons, pre-scored on fit, gives the investment committee confidence in the buy-and-build thesis and gives the platform a head start in the first year of ownership, when momentum matters most. The platforms that struggle with add-ons are often the ones that start looking for them only after closing, and end up buying whatever is available rather than what the plan required.