What this covers
- Onboarding and intake are different jobs. Onboarding happens once. Intake happens every year.
- Eight stages between saying yes to a client and starting their first return.
- The prior-year return is the most valuable thing you collect, and the most often skipped.
- A client onboarded badly in January stays expensive for three seasons.
Client onboarding is everything between deciding to accept a client and being able to start work for them. Acceptance, the engagement letter, authorizations, prior-year records, systems access, and the internal handoff to whoever will do the work.
Most firms treat it as paperwork. It is closer to a foundation. A client onboarded properly costs less every year that follows, because the record you built at the start is the thing every later request is generated from.
This guide covers the eight stages, what to collect for different client types, and where onboarding most often fails.
DistinctionWhy onboarding is separate from intake
Firms that run them as one process end up doing both badly.
| Onboarding | Intake | |
|---|---|---|
| Frequency | Once, at the start of the relationship | Every filing period |
| Output | A client record the firm can work from | A complete document set for one return |
| Owner | Usually a partner or practice manager | Usually an admin or preparer |
| Failure mode | Missing authorizations and no prior-year context | Missing documents and chased deadlines |
| Time pressure | Low, if done outside the season | High, always |
The connection between them runs one way. Good onboarding makes every subsequent intake cheaper, because the tax organizer and the document request are both generated from what onboarding captured.
The checklistAn eight-stage client onboarding checklist
-
Client acceptance
Before anything else, decide whether to take them. Conflict check, the reason they left their previous firm, whether the work fits what the firm does, and whether the fee is realistic for the complexity. The cheapest client to onboard is the one you decline.
Ask for the previous preparer's name. A client who will not say is telling you something.
-
Engagement letter, signed before work starts
Scope, exclusions, fees, responsibilities, the cutoff date, and data handling. Signature recorded before anything else opens. The engagement letter is covered in full separately, including what the revised AICPA standards added in 2024.
-
Identity and entity details
Legal names, tax identification numbers, dates of birth for dependants, addresses, entity formation documents, state registrations, and ownership percentages for pass-through entities. Collect these once, correctly. Every error here surfaces at e-file.
-
Authorizations
Whatever your firm needs to act: e-file authorization forms, any power of attorney or information authorization required for representation or transcript access, and state-level equivalents. This is the stage most often left half-done, and it only becomes visible when someone needs to call the IRS in March.
-
Prior-year returns and carryforward items
Three years where you can get them. Federal and state. This is the highest-value item on the list and the one most often skipped because the client says they will send it later.
What it gives you: the schedules that were filed, carryforwards, elections made, depreciation schedules, state filing history, and the basis for every document request you will send for the next decade.
-
Systems access and contacts
Portal account created and tested by the client, not just invited. Preferred contact method and who is authorised to give instructions. For business clients, accounting system access and the level of that access.
"Invitation sent" is not access. Confirm they logged in.
-
Internal handoff
Assign the preparer and reviewer, set the billing arrangement, and record anything about the client that the next person needs, including how they communicate and what went wrong at their last firm.
-
First document request
Now, and only now, generate the first request from the prior-year return collected at stage five. If stage five was skipped, this request is a generic checklist and the relationship starts with a second request three weeks later.
By client typeWhat to collect, by client type
| Client type | Also collect |
|---|---|
| Individual, W-2 only | Dependant details, state residency history |
| Individual with investments | Broker account list, basis records for older holdings |
| Individual with rental property | Purchase documents, depreciation schedules, prior-year Schedule E |
| Sole proprietor or contractor | Business bank access or statements, invoicing system, payment platforms used |
| Partnership or S corporation | Formation documents, operating agreement, ownership percentages, prior-year K-1s, payroll provider |
| Multi-state | State registration history, apportionment approach used previously, nexus triggers |
| New entity, first return | Formation date, elections made or due, accounting method chosen |
The pattern is the same throughout: collect what generates future requests, not just what this year's return needs.
FailuresWhere onboarding breaks
Onboarding during the season
A client accepted in February gets a compressed version of this list, because nobody has time. Then the shortcuts become permanent, since nobody goes back to collect the prior-year return once the first return is filed.
Where the calendar allows it, onboard outside the season. Where it does not, see the next section.
The prior-year return that never arrives
The client says they will send it. Nobody follows up, because the first return got prepared without it. Two seasons later the firm still has no prior-year context for that client and nobody remembers why.
Make it a gate. The first request does not go out until it is in.
Authorizations left half-finished
Signed for federal, never done for the state. Discovered when someone needs a state transcript under deadline.
Portal invited but never used
The client received an invitation, never opened it, and sends documents by email instead. Now the firm runs two channels for one client, and the one with no audit trail is the one being used.
No record of why they left their last firm
It is the single most useful thing you can know about a new client, it is free, and it is almost never written down.
TimingOnboarding a client mid-season
Sometimes there is no choice. A compressed version that does not create debt:
- Do not skip: engagement letter, identity details, authorizations, portal access confirmed
- Do not skip, even under pressure: the prior-year return. If it genuinely cannot be obtained, request a transcript rather than proceeding blind
- Can wait until after the deadline: full three-year history, detailed carryforward review, business system access, the complete client profile
- Schedule explicitly: a date after the deadline to finish the list, assigned to a person
The last point is the one that matters. "We will finish onboarding later" without a date and an owner means never.
ProductHow TaxFlo fits
TaxFlo covers stages six through eight: the client's portal access, the first document request built from the prior-year return, and the handoff into preparer review.
The client receives an invitation, works through a stepper built around their situation rather than a generic list, attaches documents already held in their vault, uploads the rest, and submits. The firm sees the same completeness state from the provider workspace, which answers "has this new client actually started" without an email.
Stages one through five stay with the firm, as they should. Acceptance and authorization are judgement and compliance, not workflow.
Approved firms sign in through the provider workspace. If your firm is not set up yet, apply as a provider or talk to us about your intake process.
QuestionsFrequently asked questions
What is client onboarding for an accounting firm?
Client onboarding is everything between accepting a new client and being able to start work for them: acceptance and conflict checks, the signed engagement letter, identity and entity details, authorizations, prior-year returns, systems access, the internal handoff, and the first document request.
How is onboarding different from tax intake?
Onboarding happens once, at the start of the relationship, and produces a client record the firm works from. Intake happens every filing period and produces a complete document set for one return. Good onboarding makes every subsequent intake cheaper, because the request list is generated from what onboarding captured.
What should be collected when onboarding a new tax client?
Identity and entity details, signed engagement letter, e-file and information authorizations, prior-year returns for up to three years, portal access confirmed as used rather than just invited, preferred contacts, and who is authorised to give instructions. Business clients add formation documents, ownership percentages and accounting system access.
Why does the prior-year return matter so much?
It shows the schedules that were filed, carryforwards, elections, depreciation, and state filing history. It is the basis for every document request the firm will send that client in future. Skipping it means every year's request starts from a generic template instead of that client's actual situation.
When is the best time to onboard a new client?
Outside the filing season wherever possible. A client onboarded in February gets a compressed process, and the shortcuts tend to become permanent because nobody returns to finish the list once the first return is filed.
Can a firm onboard a client mid-season?
Yes, with a reduced list. Do not skip the engagement letter, identity details, authorizations, confirmed portal access, or the prior-year return. Everything else can wait, provided a specific date and a named owner are set for finishing it.
Sources
This post covers firm practice management and contains no statutory or standards claims requiring citation. Where it touches engagement letters and professional standards, see our engagement letter guide, which cites AICPA sources.
Published by AmitaSoft LLC. This is practice guidance, not tax or legal advice for any specific engagement.