New York business owners miss tax deadlines not because they are careless but because the deadlines are spread across federal, state, city, and sales tax calendars that do not align. This is a month-by-month calendar of the deadlines Westchester owners miss most often, with the penalty cost of each miss. It is evergreen and updated annually.
The single most expensive miss is not a specific deadline. It is the assumption that your accountant is tracking all of these for you without a conversation. If you do not know who is responsible for each filing, you are the one who is responsible, and the penalties compound.
January
January 31: W-2s to employees and the SSA. 1099-NEC to contractors. Fourth-quarter federal estimated tax payment. NYS-45 (quarterly payroll return) for Q4. Sales tax quarterly filing for Q4 (if on quarterly schedule).
Penalty for a late W-2: up to $310 per form. Penalty for a late 1099: up to $310 per form. These add up fast with multiple employees.
February
February 28: 1099-NEC filing with the IRS (if paper). March 31 if electronic, which is the default for most filers.
No major NYS deadlines, but this is the month to confirm your PTET election for the current tax year if you have not already.
March
March 15: S-Corp and partnership tax return deadline (Form 1120-S, Form 1065). This is the deadline owners miss most often because it is a month before the personal return deadline. File an extension if you need it, but remember an extension to file is not an extension to pay.
Penalty for a late S-Corp return: $220 per shareholder per month, for up to 12 months. A five-shareholder S-Corp that files three months late owes $3,300 in penalties.
April
April 15: Personal tax return (Form 1040). C-Corp return (Form 1120). First-quarter federal and NYS estimated tax payments. Q1 sales tax filing (if quarterly). NYS personal property return where applicable.
This is the heaviest month. If you have not finished the S-Corp return by March 15, the K-1 is not ready for the personal return, and the April 15 deadline becomes a scramble.
May
May 15: NYS partnership return deadline if extended. No major federal deadlines. This is a quiet month for filings but a good month to review quarterly estimated payments against actual income.
June
June 15: Second-quarter federal and NYS estimated tax payments (for individuals). Q2 sales tax filing if on quarterly schedule. NYS-45 for Q2.
July
No major deadlines. Mid-year is the time to review your estimated tax position. If your business is growing, your Q1 and Q2 estimated payments may be too low, and the underpayment penalty accrues.
August
August 31: NYS-45 for Q3 (if on a different cycle). Generally a quiet month.
September
September 15: Third-quarter federal and NYS estimated tax payments. S-Corp and partnership extended return deadline. If you extended the March 15 return, this is the last day to file without a late-filing penalty.
Missing the September 15 extended deadline means the late-filing penalty from March 15 continues to accrue. This is the second most expensive miss after the original March deadline.
October
October 15: Extended personal return deadline (Form 1040). Extended C-Corp return deadline. If you extended the personal return in April, this is the final deadline.
November
No major deadlines. This is the month to confirm your PTET election for the following tax year and to begin year-end tax planning. Waiting until December limits your options.
December
December 31: Last day for most year-end tax planning moves: retirement contributions, equipment purchases under Section 179, charitable contributions, owner compensation adjustments. NYS PTET optional estimated payment for the following tax year.
What Does Each Miss Actually Cost?
Late federal estimated tax: interest plus a penalty that runs roughly 8 percent annualized on the underpayment. Late NYS estimated tax: similar, with NYS interest rates. Late sales tax filing: NYS penalty plus interest, and repeated misses can trigger a sales tax permit revocation. Late payroll filings: per-form penalties that scale with the number of employees and the delay.
The cost of a miss is rarely the penalty alone. It is the penalty plus the interest plus the time cost of resolving it plus the relationship cost with the taxing authority. A business that misses repeatedly gets flagged for audit.
Who Is Responsible for Each Filing?
If you have an accountant, confirm in writing which filings they handle and which you handle. If you handle payroll internally, the W-2 and 1099 deadlines are yours. If your accountant handles the returns, the estimated payments may still be yours to make on time even if the return is on extension.
The most common miss is not a forgotten deadline. It is an assumed deadline, where both the owner and the accountant thought the other was filing it. If you are not sure, ask. The call is free.
Daniel W. Correa, CPA, PhD
Founder, President and CEO, The C2 Group Inc.
BBA in Accounting, St. Francis College, New York. More than 50 years advising owners and boards. CPA, PhD. Member of New York State Society of CPAs and American Institute of Certified Public Accountants.
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