How much should I set aside for my next quarterly estimated tax payment on trading profits?

How this is calculated

• The federal safe-harbor rule lets you avoid an underpayment penalty by paying, across the year in four installments, the smaller of 90% of this year's actual tax or 100% of last year's tax (110% if last year's adjusted gross income was over $150,000, or $75,000 married filing separately).
• This tool calculates the smaller of those two safe-harbor totals, if you provide last year's tax, then divides it evenly across quarters and subtracts what you've already paid this year to show what's due now.
• If you only enter this year's estimated tax, the tool uses the 90%-of-current-year safe harbor on its own, since it has no prior-year figure to compare against.
• This does not account for withholding from a W-2 job, which counts toward your safe harbor the same as an estimated payment does, or for state estimated tax rules, which run separately from federal ones.
• Quarterly due dates don't line up with calendar quarters exactly; confirm the actual IRS due dates for the current tax year before paying.