There are 2 penalties ... paying on time saves you the FAILURE TO PAY penalty  however  although the TT program calculates an estimated UNDERPAYMENT penalty based on the info you entered on the tax return the IRS/State reserve the right to compute the underpayment penalty based on the info they have and send you a bill for the extra amount.

What are estimated taxes?

https://ttlc.intuit.com/replies/3301588

Do I need to make estimated tax payments to the IRS?

PAYING ESTIMATES
For SE self employment tax - if you have a net profit (after expenses) of $400 or more you will pay 15.3% for  SE Tax on 92.35% of your net profit in addition to your regular income tax on it. So if you have other income like W2 income your extra business income might put you into a higher tax bracket.

You must make quarterly estimated tax payments for the current tax year (or next year) if both of the following apply:
- 1. You expect to owe at least $1,000 in tax for the current tax year, after subtracting your withholding and credits. 
 
- 2. You expect your withholding and credits to be less than the smaller of: 
    90% of the tax to be shown on your current year’s tax return, or 
  100% of the tax shown on your prior year’s tax return. (Your prior year tax return must cover all 12 months.)