If you wish to make changes to a trust income tax return that has already been filed, complete form TP-646.R-V, Request for an Adjustment to a Trust Income Tax Return. You are not required to file a new income tax return for the trust. However, if the requested adjustment changes the allocation of income to the trust's beneficiaries, you must enclose an amended Schedule C of the Trust Income Tax Return (TP-646-V) and amended RL-16 slips (see courtesy translation RL-16-T).

If, after processing a request for an adjustment, a reassessment results in the reduction of the trust's balance due and entitles the trust to a refund of income tax, interest or penalties, we must grant the refund if the request was submitted to us within:

• three years (four years in the case of a mutual fund trust) after the end of the taxation year concerned;
• six years (seven years in the case of a mutual fund trust) after the end of the taxation year concerned, if the trust requests the carry-back of certain deductions or changes the amount of such a carry-back.

In certain cases, we have the discretionary power to issue a refund without taking into account the above time periods. We will generally accept a request for an adjustment submitted to us within six years (eight years in the case of a mutual fund trust) after the end of the taxation year concerned.

Only a graduated rate estate can request a refund after the expiry of the prescribed period, provided the adjustment request is submitted before the end of the 10th calendar year after the taxation year concerned. For example, if the taxation year concerned is 2013, you have until the end of the 2023 calendar year to request an adjustment. However, a testamentary trust can request an adjustment for taxation years ended before December 31, 2016.

We may not issue a refund if the request for an adjustment aims to increase a deduction, where the trust initially elected not to claim the maximum amount allowed. We will also not issue a refund if the request is made for retroactive tax planning purposes.