The short answer: CRA record, prior filings, then the books, in that order
A proper onboarding is a reconciliation of three versions of your business that are supposed to agree and often do not. The CRA's version lives in its program accounts. The filed version lives in your past returns and slips. The internal version lives in your accounting file. When all three match, onboarding is quick and the new relationship starts at planning. When they diverge, the divergence is exactly where penalties, interest and reassessments come from, and finding it in month one is the whole point.
The order is deliberate. Starting with the CRA record means every later check has an anchor: a return is not "done" because a PDF exists, it is done because the CRA shows it assessed. Starting with the books, which is what a rushed takeover does, means building on numbers nobody has verified against anything.
If you are still deciding whether to move firms at all, start with the signs you have outgrown your current accountant; this page assumes the decision is made and the handover is underway.
Layer one: every CRA program account, read end to end
The first concrete act of onboarding is authorization: the new CPA files an authorization request through the CRA's Represent a Client service, per program account, and the old firm's stale access gets cancelled. Until that happens the new accountant is working blind, so this belongs in week one. Then each account gets read the way a doctor reads a chart, history first.
Each program account answers different questions:
| Account | What the new CPA checks |
|---|---|
| Corporate income tax (RC) | Every expected T2 assessed, balances and interest, instalment history against what the year's income will require, any open reviews |
| GST/HST (RT) | Assigned filing frequency, all periods filed, net tax paid against the revenue the books show, credits or arrears sitting unexplained |
| Payroll (RP) | Remittance frequency and history, T4 summaries matching what was remitted, any PIER reports or discrepancy letters |
| Correspondence, all accounts | Letters issued in the last few years, especially review requests and proposals nobody answered |
| Ontario programs (EHT, WSIB) | Registration where payroll size requires it, filings current, rates and classifications still correct |
Two findings from this layer change everything that follows. Unanswered correspondence means deadlines may already be running, and responding jumps to the front of the queue. And instalment shortfalls mean interest is accruing quietly right now, which no amount of good bookkeeping will show you, because instalment interest exists only in the CRA's ledger.
Layer two: the prior filings, re-read with fresh eyes
The new CPA does not re-audit history; they re-perform enough of the recent filings to know whether the pattern is sound. That usually means reading the last two or three corporate returns line by line, testing the big judgment calls, and tracing the carryforward balances that quietly control your future tax: loss carryforwards, undepreciated capital cost by class, the capital dividend account, refundable tax balances, and the shareholder loan history. These balances outlive the accountant who calculated them, and errors in them compound silently until someone checks.
When something is wrong, there is a defined path for each kind of wrong. Corporate returns are corrected through amended filings or adjustment requests. HST errors are fixed in a current return within limits or through an adjustment request. Slips are amended and refiled. Where income was never reported at all, a voluntary disclosure, filed before the CRA initiates contact, can reduce penalty exposure. The incoming firm quantifies the correction, the tax, the penalties and interest, and tells you plainly whether fixing it costs less than it saves; most corrections are undramatic once someone owns them.
Penalties and interest deserve one honest paragraph. Interest compounds daily on balances and is not deductible; late-filing penalties are a percentage of tax owing that escalates for repeat failures. Where a failure traces to circumstances beyond your control, or to reliance on wrong professional advice, the taxpayer relief provisions let the CRA cancel or waive penalties and interest on request. Relief is discretionary, not automatic, and a well-documented request written by someone who has read the whole file succeeds far more often than an apology letter. This corrective work is the heart of a CRA support engagement, and it is why owners searching for a CRA support and corporate compliance CPA in Ontario are usually mid-transition when they search.
This layer is also where the previous accountant's working papers earn their keep. Adjusting entries, reconciliations and carryforward schedules explain why the filed numbers are what they are; without them, the new firm rebuilds history at your expense. Request them as part of the handover, using the list in what records to request from your previous accountant.
Layer three: the books, tied to the last filed return
The internal file is only trustworthy once its opening position is tied, account by account, to the final trial balance behind the last filed return. That tie-out is the single most valuable hour of onboarding, because every future statement builds on those balances. Differences are common and usually explainable: year-end adjusting entries the old firm booked in their file but never pushed back into yours is the classic case. Unexplained differences are the ones that matter.
Then the balance sheet gets a credibility pass, because the balance sheet is where bookkeeping problems hide. Bank and credit card accounts should reconcile to statements. The HST accounts should track what the RT account shows filed and paid. Payroll liabilities should equal the next remittance, no more. Inter-company balances should mirror each other exactly across related entities. And the shareholder loan account gets special attention, because a debit balance there has personal tax consequences on a timeline, and it is the account most likely to have been treated as a dumping ground.
The review also looks at how the books are produced: the software, who posts what, and where the process depends on one person's memory. Sometimes onboarding ends with "the bookkeeping is sound, carry on." Sometimes it ends with a rebuild recommendation. Either way you deserve the verdict in writing, with reasons.
What you get at the end: a calendar, a baseline and a priority list
Onboarding should finish with three deliverables, and you should expect all three in writing. First, a twelve-month compliance calendar: the T2 filing deadline six months after year-end and the balance-due date that arrives earlier, HST at your assigned frequency, payroll remittances on their schedule, T4 and T5 slips at the end of February, and the Ontario items that apply to you, each with a named owner. Missed deadlines during and after transitions are almost always ownership failures, not knowledge failures; the calendar is the cure.
Second, a records baseline. The CRA generally requires books and records to be kept for six years from the end of the tax year they relate to, and that obligation is yours, not your accountant's. Onboarding is when the new firm confirms what exists, where it lives, and what gaps need filling while documents can still be recovered from banks and suppliers.
Third, a priority list with numbers attached: what needs correcting, what it costs, what can wait, and what planning opportunities the review surfaced, because reading three years of returns almost always surfaces some. That list is also your quality check on the firm itself. An onboarding that produced no findings and no calendar was a file transfer, not a review. The broader sequencing of the switch, notice, timing and cutover, is covered in how to change accountants without disrupting your business.
What changes how deep the review goes
Onboarding depth is a judgment call, and these are the facts that move it:
- The state of the CRA accounts. Clean accounts support a light-touch review. Arrears, unfiled periods or open reviews turn onboarding into a cleanup engagement with deadlines.
- How long since anyone independent looked. Fifteen years with one preparer means fifteen years of unexamined habits, good and bad.
- Entity count. Holding companies, sister companies and inter-company balances multiply the tie-out work and the places errors hide.
- Payroll size and complexity. More employees means more remittance risk, and payroll penalties escalate fast.
- How the owner is paid. Salary, dividends, and the shareholder loan account each leave different trails, and the loan account is checked hardest.
- What is coming. A planned financing, sale or reorganization raises the standard, because those transactions expose the file to outside scrutiny.
We run this review as the opening phase of every Ongoing Financial Partnership, and the scope conversation starts with a free 15-minute discovery call.
Source: CRA — Keeping records.
