Self-Employed but Not actively working

Individuals, including sole proprietors, partners, and S corporation shareholders, generally have to make estimated tax payments if they expect to owe tax of $1,000 or more when their return is filed. Individuals, including sole proprietors, partners, and S corporation shareholders, generally use Form 1040-ES, to figure estimated tax.

You don’t have to pay estimated tax for the current year if you meet all three of the following conditions.

• You had no tax liability for the prior year
• You were a U.S. citizen or resident alien for the whole year
• Your prior tax year covered a 12-month period

You had no tax liability for the prior year if your total tax was zero or you didn’t have to file an income tax return. 

https://www.irs.gov/businesses/small-businesses-self-employed/estimated-taxes 

@isab1 Thanks for the question!!