Direct answer
In the first 100 days after buying a business, reconcile the records before you change the systems: customers, open jobs, invoices, staff and compliance. Then find the loops that still run through the previous owner, and move the busiest one into systems the business owns. Leave new software until you know what the old setup actually does.
The plan below runs over 14 weeks, which is roughly 100 days. It covers systems, records and reporting, the operational side of taking over. It is not financial or legal advice, and it doesn't replace your accountant, solicitor or lender; check anything about warranties, the sale agreement, tax or employment law with them.
Weeks 1–2: inventory what you inherited
You bought the business, but you may not yet control all of it. Many owner-managed firms run on accounts opened in the previous owner's name, passwords in one person's head and knowledge nobody wrote down. Before you change anything, find out what you actually have.
Make four lists.
Systems. Every piece of software the business uses: accounts, CRM, job management, booking, email, website, payroll, phone system, file storage, the spreadsheets that matter. For each, note who pays for it, whose email the account is registered to, and who has admin access.
Logins and ownership. Move every business account to a business email address you control, and change the admin passwords. Pay particular attention to the domain name, email, the bank feed into the accounts software and anything paid for on the previous owner's personal card. If an account can't be moved yet, write down who holds it and agree a date.
Data. Where each kind of record lives: customers, open jobs, quotes, invoices, debtors, staff records, the records your sector requires. Note where the same record is kept in two places, because that's where they'll disagree.
Who knows what. For each regular task, who does it now and who did it before completion. Pay attention to anything only the previous owner did. The handover period in your sale agreement, if there is one, is the time to get that knowledge out of their head and onto paper.
Don't switch systems in these two weeks. You don't yet know which quirks are mistakes and which are there for a reason.
Weeks 3–6: reconcile customers, open jobs, invoices, staff and compliance records
Reconciling means checking that records which should agree actually do. It is slow and dull, and it's the most useful thing you can do in your first two months, because every later decision rests on these numbers.
Swipe or scroll to compare the columns.
| Records | Reconcile against | What you're looking for |
|---|---|---|
| Customers | Accounts software and CRM | The same customer under different names; customers in one system and not the other; who really owns each relationship |
| Open jobs and orders | Quotes, the job system and what the team says is in progress | Jobs nobody has invoiced, jobs promised verbally, deposits taken for work not started |
| Invoices and debtors | Aged debtors against the bank and the chasing record | Old debts that will never be paid, credit notes agreed but never raised, payment plans nobody wrote down |
| Suppliers and costs | Bills and direct debits against what the business actually uses | Subscriptions for software nobody uses, contracts that auto-renew |
| Staff | Contracts, payroll, holiday and absence records | Staff missing from one list, holiday balances nobody can explain, terms that differ from the contract |
| Required records | Whatever your sector requires: safety, waste, tenancy, staff | Gaps in dates, records kept on paper or by one person |
Where you find a difference, record it, fix it in the system of record, and note why it happened. Some differences will matter to the sale agreement; if a debt in the completion accounts turns out not to exist, tell your accountant or solicitor rather than writing it off quietly.
Pick one system of record for each kind of data now, even if you plan to change systems later. Customers live in the CRM, or in the accounts software if there isn't one. Invoices live in the accounts software. Jobs live in the job system. Everything else reads from those.
Weeks 7–10: find the loops still running through the seller, and move the busiest one
By week seven you'll have noticed which things wait for the previous owner, or now wait for you because you inherited their role. These are the loops: enquiries that only they answered, prices only they knew, invoices they typed, reports they pulled from three systems by hand, records only they could find.
List them, and for each one count how often it happens in a week. An enquiry loop that fires 40 times a week matters more than a monthly report. Then pick the busiest loop and move it into systems the business owns.
What that looks like depends on the loop:
- Enquiries: a first reply and booking step on every channel, with a named person for the cases a system shouldn't handle. Where WhatsApp or web chat carries the volume, an AI agent can collect details and book, with a person taking over complex conversations; our WhatsApp order processing case shows the pattern.
- Quotes to cash: write the pricing rules down first, then connect the accepted quote to the deposit invoice and the reminders, so nobody re-types them.
- Reports: agree the five or six numbers you need weekly and where each comes from, then have them arrive on a schedule.
- Records: capture them as the work happens, inside the tools the team already uses.
Rules handle what must be exact, AI handles what needs judgement, and a person signs off where mistakes are expensive. In a business you've just bought, keep the sign-off step generous at first. You're still learning where the expensive mistakes are.
Count before and after: how many times a week the loop needed you before the change, and how many times after. If the four-week owner-absence test is useful, take it now and again at day 100.
Weeks 11–14: a reporting baseline, so the next owner (or lender) can read the business
By the last month you should be able to answer "how is the business doing?" from the systems rather than from memory. Set up a baseline: a short weekly brief from the systems of record covering sales, cash in, cash owed, jobs completed, jobs at risk and anything your lender reports on.
Define each number in writing. "Sales" can mean quotes accepted, invoices raised or cash received, and the previous owner may have used a different meaning from your lender. Write down which one you use, where it comes from, and who checks it.
The baseline does three jobs. It tells you whether the changes you've made are working. It gives a lender or investor figures they can check against the accounts. And if you ever sell, it's the start of the record a buyer will test; our diligence checklist covers what they ask for.
What not to change in the first 100 days
New owners often want to replace the software early. Usually it's better to wait.
- Don't replace the accounts software, CRM or job system until the records in it reconcile. Migrating data you haven't checked moves the errors to a new home.
- Don't change prices or payment terms with long-standing customers until you know who holds each relationship and why the terms are what they are.
- Don't remove a manual step until you know why it's there. Some odd routines exist because of a customer, a regulator or a past mistake.
- Don't buy a new tool to fix a problem you found in week three. Write the problem down, and decide at day 100 with the whole list in front of you.
- Don't automate a loop whose rules nobody has written down. Automating guesswork makes mistakes faster.
What you can change straight away: account ownership and passwords, anything that is plainly a security risk, and subscriptions nobody uses.
At day 100 you'll have an inventory, reconciled records, one loop out of the previous owner's hands, and a weekly baseline. That is the point to decide what to replace and in what order. If you'd rather have help from the start, our Audit (£3,500 excl. VAT) can be week one of a plan like this: it maps one loop end to end and prices the work to take it out. Book a 100-day systems call.
