Due to the pandemic I had a loss of income for my company. How can I write that in my taxes? Loss of services?

[JoannaB2]

When your self-employment income was not enough to cover your expenses, you have a business loss. If the business loss cannot be deducted against other sources of income because there is not enough, the loss can be carried back for two years or forward for 20 years. If there was no taxable income in the past two years, the losses may be carried forward for 20 years or until there is a year with taxable income to claim the losses against. 

Self-employed business owners can deduct legitimate business-related expenses against their revenues to arrive at the net business income for the year

[Carl]

You can not claim a deduction for income that you never received in the first place, and therefore never paid taxes on. The lower income must means you pay less in taxes.