What is the rule for self employed tax payment to avoid to be late and have penalties?

[KittyM]

For 2018, the final payment date is April 15, 2019.  Anything after that is late and will accrue penalties and interest.

If you are required to make quarterly estimated payments, the payment due dates are generally as follows:

• April 15 of the current year for the current filing year (e.g. 4/15/2019)
• June 15 of the current year for the current filing year (e.g. 6/15/2019)
• September 15 of the current year for the current filing year (e.g. 9/15/2019) 
• January 15 of the following year for the previous filing year (e.g. 1/15/2020)
• April 15 of the following year for any remaining balance due. (e.g. 4/15/2020)

These payments are not evenly spaced, even though they are called "quarterly payments".  If you fail to make one on time, you may be subject to penalties and interest on the late estimated payment when you file your return.

[nuxclass]

How could I know if it's required or not? What are the rules to say if I am late or not

[KittyM]

All the details are on the IRS web page <a rel="nofollow" target="_blank" href="https://www.irs.gov/businesses/small-businesses-self-employed/estimated-taxes">https://www.irs.gov/b...>

[nuxclass]

Are the four amount value equal ? Can I decide to pay more or less depending on my income during the year?

[KittyM]

Yes, the amounts are equal, because they should add up to the same amount as your 2018 tax.  This helps to avoid penalties.  If you expect to owe more or less, you may adjust the amount you send.