Before you agree to anything
Ask what the client needs, what shape the books are in and what they hope will change. Ask which software they use, who has access, how many accounts they have and whether anyone else has been doing the books. A short intake call or form gets this on record.
Be willing to decline. If the books are badly behind, the scope may need to start as a cleanup. If the client wants tax advice, say it is for a CPA.
Put the scope in writing
A short agreement should state what you will do each month, what you will not do, how often you will report, what you need from the client and by when, how you are paid and how either side can end the arrangement. Be specific about reconciliations, payroll, sales tax and anything that is extra.
Plain English works better than legal language, and a lawyer should review any agreement you reuse. Do not copy another firm's terms without checking them.
Set up access and a baseline
Get access to the accounting software, bank and card feeds, and payment processors under the client's own logins, so they keep control. Record the opening balances and the date the clean books begin. Note anything unreconciled as of that date.
Take a snapshot of the books before you change anything. If something looks different later, you will know why.
Common onboarding mistakes
Starting work before the agreement is signed. If the scope is vague, the first dispute is about what you were supposed to do. Taking over books without checking the opening balances is another. If the beginning is wrong, every report after it is wrong. A third is accepting the client's login instead of having them add you as a user, which makes it hard to show who changed what.
Skipping the first-month review is the last one. Small misunderstandings grow when nobody checks in. A short call after the first close often turns a good start into a long engagement.
Create the monthly request
Tell the client what you need each month and by which day: statements, receipts for items you cannot match, payroll reports and answers to questions. A fixed list and a fixed date makes the habit easy for both of you.
Send the same message on the same day each month. Clients do better with a rhythm than with ad hoc requests.
Review after the first close
After the first month, send a short summary of what you found, what you changed and what you need. Ask whether the reports answer their questions. Adjust the scope if you learn the client wanted something else.
The onboarding documents are the part you can write once and reuse. The Bookkeeping Client Onboarding Pack on this site holds a questionnaire, an engagement letter draft and checklists in editable files, and your lawyer should review the agreements before you use them.
Common questions
Do I need a written agreement for every client?
It is strongly recommended. It sets expectations and protects both sides. Have a lawyer review your template.
What if the client does not send documents on time?
Say in the agreement what happens, such as delayed reports, and remind them on a schedule.
Should I charge for the onboarding?
That is your decision. Many bookkeepers fold it into the first month or charge a setup fee.
This guide is general information, not tax, legal or accounting advice. Rules, fees and due dates change; check with the IRS, the NJ Division of Taxation or a licensed professional for your situation.