I started a E-commerce business in 2021. I had start-up AND monthly expenses but did not generate any revenue. Do I file a Schedule C and deduct the (qualified) expenses?

Expenses are deducted in the year incurred. You can take start-up costs even without income. However, the IRS does expect to see a profit soon.

Start up costs are those expenses incurred in planning and setting up the business, costs you incur before you open the door.

A portion of startup and organizational costs can be expensed (written off in your first year). The remainder can be amortized (written off over a period of 15 or more years). 

Here is how it works:

Expenses paid or incurred after October 22, 2004: 

 - You can deduct up to $5,000 in startup and $5,000 organizational costs as current expenses if the costs are under $50,000, respectively.

 - You can choose to amortize startup and organizational costs greater than $5,000, respectively, (but less than $50,000, respectively) over a period of 15 years.

 - If your startup or your organizational costs are more than $50,000, respectively, the excess amount reduces the amount you can deduct.

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Note: A cash-basis business cannot deduct or write off (amortize) these costs until they are actually paid.

For example:

You opened a pet supply store in January 2020. You spent $52,000 to research the market, paint the building, hire a handyman to install shelves, pay for electricity and phone service before you opened the door to customers.

You can deduct $3,000 worth of startup costs as a current expense in 2016: $5,000 - ($52,000 - $50,000) = $3,000. And you can amortize the remaining $49,000 over 15 years.