Quarterly Taxes Agent Skill

Quarterly Tax Estimator

Overview

Calculates estimated quarterly tax payments for self-employed individuals and business owners filing Form 1040-ES. Uses your year-to-date income, effective tax rate, and IRS safe harbor rules to determine how much to pay each quarter.

Wilson Tools Used

• spending_summary — Pull income totals for the current tax year
• transaction_search — Find estimated tax payments already made (IRS, state tax authority)
• export_transactions — Export payment history for recordkeeping

Workflow

• Use spending_summary to get total income received year-to-date.
• Project annual income: (YTD income / months elapsed) x 12.
• Determine your effective tax rate. If unknown, use 25-30% as a starting estimate for federal + self-employment tax.
• Calculate annual estimated tax: projected annual income x effective tax rate.
• Divide by 4 to get the quarterly payment amount.
• Use transaction_search to find payments already made to "IRS," "EFTPS," "US Treasury," or your state tax authority.
• Subtract payments already made from the amount due for the current quarter.
• Apply safe harbor rules (see below) to determine the minimum payment to avoid penalties.

Quarterly Due Dates (Form 1040-ES)

| Quarter | Income Period | Due Date |

|---------|--------------|----------|

| Q1 | Jan 1 – Mar 31 | April 15 |

| Q2 | Apr 1 – May 31 | June 15 |

| Q3 | Jun 1 – Aug 31 | September 15 |

| Q4 | Sep 1 – Dec 31 | January 15 (following year) |

Safe Harbor Rules

To avoid underpayment penalties, you must pay the lesser of:

• 100% of prior year tax liability divided by 4 (110% if prior year AGI exceeded $150K, or $75K if married filing separately)
• 90% of current year tax liability divided by 4

If your income is uneven throughout the year, you can use the annualized installment method (Form 2210, Schedule AI) to potentially reduce earlier quarter payments.

Estimation Formula

quarterly_payment = (projected_annual_income x effective_tax_rate) / 4
amount_due = quarterly_payment - payments_already_made_this_quarter

Without Wilson

• Open a spreadsheet. In cell A1, enter your total income received year-to-date.
• In B1, calculate projected annual income: =A1 / (MONTH(TODAY()) / 12).
• In C1, enter your effective tax rate as a decimal (e.g., 0.30 for 30%).
• In D1, calculate quarterly payment: =B1 * C1 / 4.
• In E1, enter estimated tax payments already made this year.
• In F1, calculate remaining per quarter: =D1 - (E1 / quarters_remaining).
• Compare against your prior year total tax (from Line 24 of your prior 1040) divided by 4.
• Pay the lesser of the two amounts to satisfy safe harbor.

Important Notes

• Self-employment tax (15.3% on 92.35% of net earnings) is separate from income tax. Include it in your effective rate.
• State estimated taxes are separate. Most states follow the same quarterly schedule but check your state's requirements.
• If you also receive W-2 income, you can increase withholding on your W-4 instead of making estimated payments.
• The penalty for underpayment is calculated per quarter, not annually. Late Q1 payments accrue penalties even if Q4 is overpaid.
• This is not tax advice. Consult a CPA or tax professional for filing decisions.