Onboarding a new accounting or bookkeeping client is mostly a collection problem. The engagement is agreed in one call; then it takes three weeks of emails to get last year's return, twelve bank statements and a login that works. Most onboarding checklists stop at "gather the client's financial documents" without saying which ones, or how to get them without the email chain.

This one follows the order the work actually happens in, with the full document list in step 5 and a copyable version at the end.

1. Know your client (KYC), before anything else

Decide whether you are taking the client before you collect a single statement. Two things belong here.

Identity and ownership. Who you are dealing with, who owns the business, and who is allowed to instruct you. In the UK and much of the EU this is not optional: accountants and bookkeepers are covered by anti-money-laundering rules and must carry out customer due diligence, which means verifying identity and beneficial ownership and keeping the record. In the US there is no general AML duty for accountants, but the same check is what stops you from filing a return for someone who is not who they say they are.

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Warning

Do the verification with a tool built for it, or in person on a video call, not by asking for a passport scan by email. A KYC tool checks the document against the face and keeps the evidence; a scan in an inbox proves nothing and sits there for years. An upload link is no better at it than an inbox: it stores the scan, it does not check it.

Fit and risk. Entity type, industry, how messy the books are, whether returns are late or notices are open. A business two years behind with an IRS letter in the drawer is a different engagement, at a different fee, from a clean monthly close. Find out now, not after you have quoted.

2. Engagement letter, signed

Scope, what is excluded, fees and how they change, deadlines, and what the client is responsible for: providing complete records on time, answering questions within a set number of days, telling you about changes. That last part is what you will point at in March.

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Tip

Two clauses save most arguments later. The document deadline and what happens after it: if records arrive after a given date, the deadline moves or an extension is filed, and you say which. Out-of-scope work is billed separately: catch-up bookkeeping, notices, amended returns.

Send it for e-signature and do not start work until it is back. Most practice management tools include this; a standalone e-signature tool does the same job.

3. Access: delegated, never shared passwords

Ask for access in a way that gives you your own login. A shared password breaks the day the client changes it, and leaves no trace of who did what.

Write down who has access to what. When the engagement ends, that list is what you revoke.

4. Prior accountant handover

If the client is switching firms, most of what you need already exists in someone else's files. Ask the client to request, or authorize you to request:

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Tip

Ask for the schedules, not the file. Returns and depreciation schedules prepared for the client are client records, and the previous accountant should hand them over on request; their working papers are theirs to keep. A depreciation schedule rebuilt from scratch costs hours and is rarely exactly right.

5. Documents: the client intake list

The rest is records. The list is long, so cut it per client; a sole proprietor does not have a shareholder agreement and a holding company often has no payroll. Ask for everything in one request, with each item named, rather than sending new requests one at a time as you discover what is missing. The client should see the whole job at once and be able to check it off.

The form names below are US ones. The shape of the list holds anywhere.

The business

History

Money in and out

People

Assets and commitments

6. Kickoff and first close

A short call once the documents are in: walk through what came, what is still missing, and anything that looked odd. Agree how the client will send things from now on, how fast you will answer, and who on their side answers your questions. Then do the first month or the catch-up, and only then move them into the recurring workflow: monthly bookkeeping or the tax cycle.

Step 5 is where onboarding usually stalls, and the reason is rarely the client's goodwill. "Send me your financial documents" produces a few attachments, a forwarded email thread and a photo of a page. A named list produces a folder.

That is the one job 500files.com does:

To set one up, create a page titled for the client, paste the list below into the checklist, one line per item, delete what does not apply, and send the link with your welcome email. If you want wording for that email and the follow-ups, we wrote six document request emails.

The list in short form, ready to paste - each line becomes its own checklist item:

Articles of incorporation or organization
Operating or shareholder agreement
EIN confirmation letter (CP 575)
S-corp election acceptance notice (CP261)
Business licenses and sales tax registrations
Business tax returns - last 3 years
Prior-year financial statements and closing trial balance
Fixed asset and depreciation schedule
Open notices from tax authorities
Bank statements - all accounts
Credit card statements - all cards
Loan and lease agreements with latest balances
Payment processor and marketplace reports
Accounts receivable and payable aging
Payroll registers and quarterly payroll filings
W-2, W-3, 1099-NEC and 1099-MISC copies issued
Contractor W-9s
Purchase documents for property, vehicles, equipment
Insurance policies
Major customer and supplier contracts

It is free, and if a paid plan comes, the person you send the link to will still not need an account.

What it deliberately does not do: no engagement letters or e-signature, no client record that carries over between years, no scheduled reminders. Pages expire, so the documents end up in your own system rather than ours. Identity documents stay with your KYC tool (step 1). If you need the record system and the workflow too, a practice management tool is the right purchase; we compared the options in Karbon alternatives and nine client portals.