The first 100 days after an acquisition closes

The plan has eight stages because the constraints arrive in that order. Day 1 is defined by the things that cannot be re-run: a signatory change, an insurance binder whose effective time is a time and not a date, payroll continuity, and control of the domain and the password vault. Week 1 is cash and inventory. Weeks 2–4 are listening. Days 30–60 are extraction — pulling the business out of the seller's head while the seller is still standing in the building. Days 60–90 install a pulse. The Day 100 mark is a review, not a milestone.

The seven workstreams that run underneath are cash and finance, people and payroll, customers, systems and data, legal and insurance and licensing, operations and safety, and pricing. Seven is the honest number at ten to a hundred headcount. Corporate post-merger integration decomposes into far more, with an integration management office to coordinate them, and that structure does not survive contact with a company where the operator is also the person answering the phone at four o'clock.

Two plan shapes both work and they are not interchangeable. A week-by-week plan — weeks 1–2, 3–4, 5–8, 9–13 — suits a first-time acquirer who needs the calendar to carry the cognitive load. A phase-based plan — stabilise, diagnose, intervene — suits a repeat operator who already knows what each phase contains. Choosing the wrong one produces either a plan nobody can execute or a plan nobody needs.

A Day-1 item is executable at 00:01 or it is not a Day-1 item. That test disqualifies most of what first-time acquirers put on their Day-1 list and promotes a set of unglamorous obligations in its place: whether the change of ownership requires a new employer identification number, whether the trade licence transfers at all or has to be re-issued against the new entity, whether the insurance and benefits coverage that was bound to the seller's entity has been re-papered with an effective time that leaves no gap, and whether the payroll run scheduled for this week will actually go out.

Several of these are jurisdiction-specific and none of them should be asserted from memory. The pattern to follow is to pull the governing document — the tax authority's own guidance on when a new identification number is required, the licensing board's change-of-entity procedure, the continuation-coverage rules — and work from its text. A contractor licence that does not transfer is not paperwork in the trades; it is a precondition to operating legally.

The closing window is also when wire-fraud exposure peaks and the operator is the target. Payment instructions arriving by email during a closing are the canonical attack, and the countermeasure is procedural rather than technical: a verbal callback to a number you already held, never a number contained in the message. Announcement order is the other Day-1 discipline — key employees, then all-hands, then top customers, then the rest of the customer base, then vendors, then public and licensing bodies. Getting that order wrong is a documented own-goal that costs relationships nothing else in the plan can recover.

One thing that arrives at close and is rarely used: the operational diligence file. It was written to answer 'should I sign'. The operator inherits it to answer 'what do I do Monday', and those are different questions. Sort it into three piles — findings that were priced into the deal and are now simply the business, findings that were assumed away and are now open work, and findings that need re-testing from the inside with access the diligence team never had.

Cash control comes before everything because everything else depends on it. Who can sign, who can approve a purchase order, what automatic debits exist against the operating account, and what the true daily burn is. Auto-debits nobody knew about are the most common second-week surprise in an acquired business, and they are only findable by reading a statement line by line rather than by asking.

The acquisition loan's payment date now sits at the top of the operating calendar and reframes every cash decision underneath it. This is not a finance detail; it is the structural difference between this seat and every other management seat. In the Federal Reserve's 2026 Report on Employer Firms — a convenience sample of 6,525 responses fielded between September and November 2025 — 59% of small employer firms carrying debt had used a personal guarantee. That is the assumption almost no operating-software vendor makes about its reader, and it is the assumption this page makes about you.

The inherited-stack inventory belongs in week 1, before any migration decision. Every system, its owner, its login, its renewal date, its annual cost and its data-export path. It is a boring artifact that prevents an expensive class of mistake, because you cannot sequence a migration you have not enumerated. Customer concentration converts in the same week from a pre-close risk number into a post-close relationship plan: who gets a call, in whose company, with what message.

Weeks 2 to 4 are the one-to-one round. Every employee, a consistent question set, and a short list of things never to promise in a first-month conversation. What comes out of it is a dependency map: which single people, if they left in month two, break the business. That is a different question from customer concentration and it is answered by talking to people rather than by reading the ledger.

Days 30 to 60 are for getting the business out of the seller's head. Relationships, pricing authority and tacit judgement all live there, and they leave with the seller unless they are deliberately transferred. This is the central post-close operating problem in most acquisitions of small businesses and it is the emptiest area of the published corpus, because the pre-close literature stops at the closing table and the corporate integration literature assumes a documented target.

The chart of accounts gets rebuilt in the same window, and it gets rebuilt before any accounting migration, not after. A chart of accounts that grew by accretion under the previous owner will not produce margin by service line, which means it will not feed the scorecard you are about to build. Migrating first and redesigning later means doing the work twice.

Days 60 to 90 install the pulse, not the framework. A weekly leadership meeting with a short list of numbers and one named owner per number is a pulse. Buying a branded operating system, licensing its vocabulary and running an implementation is a framework, and doing that in month three asks an inherited team to learn a new language before they have decided whether they trust you. Sequence the processes you document by what the seller alone knows, not by what is easiest to write down.

The Day 100 review grades the plan against what was written on day one, not against how the quarter felt. Then the structural decisions start: months 4 to 6 are where the finance-hire question and the first price change land, and months 7 to 12 are the migration window and the first annual plan you actually own.

Two respectable bodies of advice tell this reader opposite things. Private-equity and post-merger-integration practice says capture value inside 100 days. Stanford's search-fund primer and IESE's operating materials say year one is for learning and for not breaking anything. Both positions are documented in primary sources on both sides, both are given to the same person, and the acquisition-entrepreneurship content space does not name the contradiction.

The resolution is not a compromise tempo. It is that the two camps are answering for different risk profiles. A sponsor with a portfolio can absorb a broken company; an owner-operator carrying acquisition debt and a personal guarantee cannot. So the honest rule is asymmetric: move fast on anything that is reversible or that protects cash, and move slowly on anything that touches how the work gets done. 'Change nothing for 90 days' is folklore, and the useful content is its four exceptions — cash bleeding, a safety issue, a departing key person, and an actively toxic manager.

The transition literature also mis-specifies this seat. Watkins' four situations — new venture, turnaround, realignment, sustaining success — assume an employed leader with a boss and a mandate. The acquirer has no boss, owns the downside and carries the debt. The taxonomy needs a fifth case: inherited, profitable, undocumented, owner-dependent. Almost every failure mode in the first year traces back to being handled as one of the original four.

One more reframing worth carrying into the plan. The commonly quoted five-year small-business failure rate describes new establishments, and you did not start one — you bought a survivor. The conditional numbers are the ones that apply: of establishments reaching five years, 69.5% reach ten, and of those reaching ten, 76.1% reach fifteen (BLS Business Employment Dynamics, data through March 2025, retrieved via archive because the agency's own domain refuses requests). The base rate for what you actually own is materially better than the headline, and nobody in this category says so.