Tax Planning Calendar: What to Do Each Month

By Tom, CPA · Updated October 27, 2026

Part of: Tax Planning

TL;DR: Spread tax planning across the year: estimates in April, June, September and January, filing in April or October, a mid-year projection in July, and year-end moves in November and December.

Educational only, not tax, legal, or investment advice. Examples are illustrations, not predictions. Rules and limits change; verify current figures and talk to a qualified professional about your situation.

Tax planning is usually done in a single panicked weekend in April, which is like doing all your exercise for the year on New Year's Eve. The better approach is a calendar: a few small tasks each month, most taking under an hour. The tax code is 4 million words long; you need about 400 of them, arranged by month, to stop being surprised by your own deadlines.

This calendar covers the 2027 filing season for tax year 2026 and planning for 2027, as of Oct 2026. Dates falling on weekends or holidays shift to the next business day, and disaster postponements can change them; confirm on IRS.gov.

CPA Warning Label: Deadlines move for weekends, holidays and disasters. Confirm each date on IRS.gov before relying on it.

January

• Jan 15: 4th-quarter 2026 estimated tax payment due.
• Download year-end statements from every bank, brokerage and retirement account.
• Update W-4 for the new year if anything changed.
• Start the 2027 mileage log and business records folder.
• Employers: W-2s and many 1099-NECs due to recipients and filed by Jan 31.

February

• Collect W-2s, 1099s and 1098s as they arrive; check each against your records.
• Build a document checklist and note what is missing.
• Check that your Social Security statement (SSA-1099) and any 1099-R from retirement accounts match what you expected; mistakes in distribution codes are common.
• Gather charitable acknowledgment letters and property tax and mortgage interest statements.
• Brokerage 1099s often arrive mid-February and corrections follow; do not file early if you expect corrections.

March

• Mid-March: partnership and S corporation returns (and K-1s) generally due March 15, unless extended.
• Decide whether you need an extension; see our extension guide.
• Review last year's carryforwards, basis records and Form 8606.

April

• April 15: 2026 individual returns or extensions due, tax payment due, 1st-quarter 2027 estimate due.
• Last day for 2026 IRA and HSA contributions.
• Last day for many retirement plan contributions for self-employed people who do not extend (SEP contributions can follow the extended due date).

May and June

• June 15: 2nd-quarter 2027 estimated payment due. Also the automatic extension deadline for U.S. taxpayers abroad.
• File any amended returns for errors found during filing; see amending a return.
• Mid-year review of beneficiaries and estate documents; see estate planning basics.
• Check if a mid-year mileage rate change was announced; in 2026 the IRS raised the business rate from 72.5 to 76 cents on July 1.

July and August

• Run a mid-year tax projection with year-to-date income.
• Adjust withholding or estimates if income changed.
• Back-to-school: check 529 plans and education credits, and save tuition receipts and Form 1098-T for the education credits you plan to claim.
• Landlords: mid-year check on repairs vs improvements; see the rental property tax calendar.

September

• Sept 15: 3rd-quarter estimate due; extended partnership and S corporation returns due.
• Review open enrollment options coming up, including HSA-eligible plans. Starting in 2026, bronze and catastrophic marketplace plans are HSA-eligible.

October

• Oct 15: extended individual returns due.
• Medicare open enrollment begins Oct 15. Early retirees should check IRMAA planning, because premiums are based on income from two years earlier.
• Look at long-term care coverage; see long-term care planning.

November

• Run a year-end projection and work our year-end tax checklist.
• Plan Roth conversions, loss and gain harvesting, and charitable giving.
• Marketplace open enrollment typically starts Nov 1.
• Landlords and real estate investors: work the real estate tax planning checklist.

December

• Dec 31: deadline for Roth conversions, RMDs, 401(k) deferrals, loss harvesting, annual exclusion gifts and placing business assets in service.
• Make charitable gifts early enough to clear processing.
• Use or lose FSA balances, depending on plan rules.
• Confirm year-end payroll for household employees and S corporation owner salary.

Estimated tax dates for 2027

Note the uneven periods: the second "quarter" is two months long. People who wrongly assume equal quarters tend to learn this the expensive way.

How to make the calendar stick

1. Put every date in your digital calendar with two reminders: one week before and one day before.
2. Automate estimates. IRS Direct Pay and EFTPS let you schedule payments in advance. Schedule all four in January.
3. Batch the paperwork. A single "tax inbox" folder, physical or digital, where every tax document goes the day it arrives.
4. Use the mid-year projection. July is the most underrated tax month: early enough to change withholding, retirement deferrals and estimates, late enough to know how the year is going.
5. Create an IRS online account to see payments, notices and transcripts.
6. Add your state's dates. Most states follow the federal April deadline, but estimate dates, extension rules and forms vary.

Life events break calendars, so revisit the plan when you marry, divorce, have a child, change jobs, start a business, buy a rental, retire or move states. Each can change your filing status, withholding, estimate requirements or the deadlines that apply to you. Our filing status guide covers the status changes, and how long to keep tax records covers the filing cabinet.

Finally, notice the pattern: almost every planning move worth making has a December 31 deadline, while almost every paperwork task has an April deadline. Planning in December and paperwork in April is fine. Trying to plan in April is how people discover the year already ended.

Illustration:

Kai is self-employed and expects $80,000 of profit in 2027. Kai owed $14,000 total tax for 2026 and plans to use the 100% prior-year safe harbor.

• Four payments of $3,500 on April 15, June 15, September 15 and January 18.
• In July, Kai's mid-year review shows profit running well ahead of plan. Kai stays safe from the penalty by keeping safe-harbor payments, but sets aside extra cash for April so the balance due is not a shock.
• In November, Kai opens a SEP or solo 401(k) and plans the contribution.

Illustrative only. If prior-year AGI had exceeded $150,000, the safe harbor would require 110%.