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To switch accounting firms in Canada, you tell the new firm, give the old one written permission to hand over your files, and cancel the old firm’s access to your CRA account. The order matters. The last step is the one people do too late, or never.
How do you handle a transition between accounting firms?
Pick your timing first. The quietest moment is right after a filing, not a week before a deadline. Switch in the middle of tax time and both firms end up guessing who owns what.
Next, tell the new firm what you need: a return, payroll, sales tax, year end statements. They’ll contact the current firm, because CPA rules expect it. Ontario’s code has a rule titled Communication with predecessor and another called Co-operation with successor. The CPA Ontario pages we found don’t quote the wording, so read them if a dispute comes up. The CPABC guidance on the same two rules says the old firm must reply promptly, and must give reasonable and necessary client information on your written request.
Put that request in writing, and keep a copy. A dated email works fine. Picture Dana, who runs a small landscaping company outside Barrie and wants out after a billing mix-up. She emails the old firm on a Monday, copies the new one, and asks for last year’s file and the list of open items. Two lines, a date, a paper trail. That’s all it takes.
What if you owe the old firm money?
This is where switches stall. The CPABC guidance states that the professional duties should be followed regardless of any amount the client still owes. So an unpaid invoice shouldn’t be a reason to hold your information back. It doesn’t cancel the debt, though, and you’d still owe the bill. Pay it or dispute it on its own track.
If the old firm digs in anyway, don’t argue by phone. Repeat the request in writing, mention the rule by name, and tell the new firm what’s happening. They’ve seen this before. If it drags on, the provincial CPA body is the place to ask for help.
Which steps belong to the CRA side?
Your old accountant probably has access to your CRA account. That access doesn’t end when the contract does. The CRA says a representative’s access stays until you or they cancel it or it expires.
| Step | What to know |
|---|---|
| Authorize the new firm | Do it online in My Account or My Business Account, or on the CRA form |
| Cancel the old firm online | Takes effect immediately |
| Cancel by form AUT-01X | Mail within six months of the date you sign it |
| Keep old records | Six years from the end of the last tax year they cover |
| Predecessor’s duty | Reply promptly and supply reasonable, necessary information on written request |
The online route is the one we’d use, since it’s immediate. The CRA’s own cancellation page calls it the fastest way to cancel a representative’s authorization. Before you cancel, check that the new firm already has its own authorization, or you may lock everyone out of a filing that’s due.
What should you gather for the new firm?
Ask for last year’s return and the notice of assessment. Get prior year financial statements, the working papers for any open items, your payroll and sales tax account details, and a list of filings still due. Have a bank and loan list ready. Businesses should also bring the articles, shareholder details and any CRA letters.
If you run payroll, nobody should forget it during the move. Take a business with one employee paid $3,000 a month in Ontario. The payroll remittance calculator shows $732.02 to remit monthly, of which $229.61 is the employer share. That payment is due no matter who is mid handover.
How long will the handover take?
We couldn’t find an official timeline, and it varies with how tidy your file is. A clean personal file might move in days. A corporation with open years, payroll and a pile of loose ends takes longer, so plan for weeks and ask the new firm for their estimate in writing. Tell them about any deadline in the next 60 days on day one, not after they’ve settled in.
What goes wrong in a switch?
The common problems are plain. Nobody is named as owner of a pending filing. The old firm still has access months later. The new firm finds out about a missed instalment in October. Get a list of due dates from both sides and compare them.
Use your own numbers as a cross check. The tax instalments calculator shows whether instalments are expected, the income tax calculator gives a personal tax estimate to compare with the draft return, and the corporate tax calculator does the same for a company. A ballpark is all you need. If the draft is far off, ask why.
Sources, and how we checked them
Access and cancellation rules come from CRA pages on cancelling a representative, linked above, and the six year rule from the CRA’s page on how long to keep records. The two conduct rules come from guidance by CPABC and the rule headings in CPA Ontario’s code. The payroll figure is from our calculator using 2026 rates. We couldn’t confirm any firm’s transfer fees, so none are quoted. This site isn’t tied to the CRA, any accounting body or any firm.
Frequently asked questions
Does the old accountant have to hand over my files?
CPA rules say the predecessor must reply promptly and supply reasonable and necessary client information on your written request.
Can the old firm hold my files over unpaid fees?
CPABC guidance says the professional responsibilities apply regardless of any outstanding amount. You'd still owe the bill.
How do I remove my old accountant from my CRA account?
Remove them in My Account or My Business Account, which cancels access immediately. You can also mail form AUT-01X.
How long should I keep my old records?
The CRA says six years from the end of the last tax year the records relate to.
When is the best time to change firms?
Right after a filing, not just before a deadline. We found no official rule on timing, so this is our judgement.
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