T183CORP Retention Calculator
A signed Form T183CORP is kept for six years. Enter the transmission date to date the end of that period.
Written and reviewed by Sharad Gondaliya, CPA (Ontario), CPA Ontario Membership 61040184.
Last reviewed: November 4, 2026
Enter the transmission date above.
Gondaliya CPA Professional Corporation is a registered EFILE electronic filer. Returns are prepared and transmitted in Canada. Credentials are never shared and never used offshore.
Why the Signed Form Is Kept at All
Form T183CORP is the authorisation to transmit. It carries the figures on the return, the date and an HH:MM:SS timestamp, and it is signed by an authorized signing officer before anything is sent. Keeping it is what makes that authorisation provable afterwards.
It is not filed with the return. The Canada Revenue Agency does not receive it unless it asks for it, which is the reason the firm holds it rather than the Agency.
What Is Kept and for How Long
| What | How long | Who receives it |
|---|---|---|
| The signed Form T183CORP | Six years from transmission | Nobody, unless the Canada Revenue Agency asks |
| The transmitted return itself | Held by the Canada Revenue Agency on the corporation’s account | The Agency |
| Your CRA confirmation | Emailed to you within 3 business days | You |
| The date and HH:MM:SS timestamp on the signature | On the signed form, for the same six years | Nobody, unless the Canada Revenue Agency asks |
The T183CORP signature requirement checker takes the separate question of who may sign it.
One Signed Form for Each Tax Year
Each tax year is its own return, so each carries its own Form T183CORP with its own date and timestamp. Six quiet years filed together produce six signed forms, each with its own six-year period running from the day that year was transmitted.
They do not expire together. A run filed in one sitting still has six separate retention end dates, because the period runs from transmission rather than from the tax year.
Frequently Asked Questions
How long do you keep my signed T183CORP?
Six years from the day the return was transmitted. The calculator above dates the end of that period from the transmission date.
Is Form T183CORP sent to the Canada Revenue Agency?
No. It is not sent unless the Canada Revenue Agency asks for it. It authorises the transmission rather than forming part of it.
Do several years share one retention period?
No. Each tax year has its own signed form, and each six-year period runs from the day that year was transmitted.
Nil T2 Filing, $300.00 plus HST per tax year
Type your corporation name, pick your unfiled years, pay, and sign Form T183CORP on a secure screen. Your CRA confirmation is emailed within 3 business days.
Start Nil T2 Filing NOW