Fiscal period
You report your business income based on a fiscal period.
A fiscal period is the time between the day your business starts its business year and the day it ends its business year.
For an existing business, the fiscal period is usually 12 months. A fiscal period cannot be longer than 12 months. However, it can be shorter than 12 months in some cases, such as when a new business starts or when a business stops.
Self-employed individuals generally have to use a December 31 year-end. If you are an eligible individual, you may be able to use another method of reporting business income that allows you to have a fiscal period that does not end on December 31.
If your fiscal year-end is not December 31, see Form T1139, Reconciliation of Business Income for Tax Purposes, to calculate the amount of business income to report on your income tax return.
If you filed Form T1139 with your last income tax return, generally you have to file that form again for this year.