Extended Your Business Taxes? What to Do Before October 15

Filing a business tax extension in April has always been the right move. But the extension only bought more time to file, and many business owners in New York and Florida treat it as permission to stop thinking about taxes until October. That is where the problem starts.

Interest on any unpaid tax has been building since the original April deadline. The closer October 15 gets without clean books or a catch-up payment, the higher that number climbs. ETCPA sees this every season, and the business owners who come in late almost always owe more than they budgeted for.

This guide covers what LLC owners, S-Corp filers, and partnerships need to do right now, before the deadline becomes a problem that costs real money to fix.

What a Business Tax Extension Means for Taxes Already Owed

A business tax extension only delays the filing deadline and incurs additional charges until the filing is complete. The IRS starts charging interest on any unpaid tax from when it was incurred, and that charge runs every day without stopping. Underpayment penalties are a separate charge on top of that, and both continue to grow until the full balance is paid.

Edward Torres has filed extended business returns for Queens business owners for over 30 years, and many of the clients who come in are the ones who filed the extensions. They made no payments between April and October, and then saw the final number in September for the first time. The extension only addressed the paperwork deadline, but the tax bill kept accruing.

That is the part worth paying attention to right now.

Business Tax Deadlines That Catch Filers Off Guard

October 15 is the date most people keep in mind for extended business returns, but that is not the only deadline on the calendar. Depending on the business structure and the state in which it operates, the actual cutoff could be weeks earlier. Here is what applies to each entity type.

S-Corp and Partnership Filers

S-Corps and partnerships file on a different extended deadline from everyone else. Form 1120-S which is the form S-Corps file and Form 1065 is for partnerships both are originally filed by March 15 each year. They have an extended due date of September 15, not October 15. That is a full month earlier.

For Pass Through Entities like Partnerships and S-Corp owners in New York, there is an extra tax to be aware of called the Pass-Through Entity Tax, or PTET. Some owners opt in so they can save money on NYS and NYC taxes, and if that happens, it has its own separate payment schedule. PTET estimated payments are due March 15, June 15, September 15, and December 15 of each tax year. A pass through owner in Queens can file the federal return perfectly on time and still have an unpaid New York PTET payment sitting there because the two deadlines are tracked completely separately.

C-Corp Filers

C-Corps filing Form 1120 have an original deadline of April 15 and an extended deadline six months later on October 15. That is the latest date in the extended return calendar, and it applies to C-Corps nationwide at the federal level.

For C-Corps operating in New York City, they must file a NYS Form CT-3 and a NYC Form 2 which are General Corporation Tax returns and they follow the same original and extended deadlines as the federal Form 1120. All need to be filed, along with any outstanding balances by those dates and estimates are required to be paid in advance. A C-Corp in Queens that files the federal return on time but misses either the NYS or the NYC General Corporation Tax filings risks a late filing penalty from NYS and New York City and they do not waive those penalties easily.

C-Corp owners who have made no estimated tax payments this year are in for a higher number than they expect. The authorities expect that money way before the filing deadlines, and the interest on the unpaid balance has been growing every day since then. By October 15, the total owed is the original tax amount plus accumulated interest and penalties for many months.

LLC Owners in New York

How an LLC is taxed depends on its setup, and that detail determines which deadline applies. A single-member LLC files on the individual return by April 15 and the extended deadline by October 15. An LLC taxed as a partnership or as an S-Corp falls under the pass-through deadlines above.

LLC owners operating inside New York City have an additional tax obligation called the Unincorporated Business Tax. The UBT form requires income allocated to the city and requires a separate filing on NYC Form NYC-204. This form follows the deadlines of pass-through entities.

New York State estimated tax payments are due April 15, June 15, September 15, and January 15. LLC owners in Queens with missed payments this year are carrying an additional balance on top of their tax liabilities and all will be growing simultaneously.

Business Owners in Florida

Florida has no personal state income tax, and this makes many business owners assume their state tax obligation is zero. However, that is only true for sole proprietors and single-member LLCs taxed as individuals. C-Corps operating in Florida pay a state corporate income tax of 5.5 percent on Florida-sourced net income, filed using Form F-1120. The extended deadline for the Form F-1120 is six months from the original due date. Some LLCs that elected C-Corp status are subject to the same obligation.

Florida businesses also file an annual report with the Florida Department of Revenue by May 1 each year. Missing that date carries a $400 late fee.

Sole proprietors and single-member LLC owners in Florida still owe federal self-employment tax at 15.3 percent on net self-employment income. Having no Florida state income tax does not mean there is no tax bill. The federal obligation is still very much there.

The table below summarizes the extended deadlines by entity type. You can determine which category applies to your LLC or corporation, or confirm with a CPA before assuming October 15 is your date.

Extended Deadline Summary by Entity Type

S-Corp (Form 1120-S) — Federal: September 15 | NY: September 15 (PTET tracked separately) | FL: N/A

Partnership (Form 1065) — Federal: September 15 | NY: September 15 | FL: N/A

LLC taxed as Partnership — Federal: September 15 | NY: September 15 | FL: N/A

LLC taxed as S-Corp — Federal: September 15 | NY: September 15 (PTET tracked separately) | FL: N/A

C-Corp (Form 1120) — Federal: October 15 | NY: October 15 (NYS & NYC General Corporation Tax mirrors federal) | FL: 6 months from original due (Form F-1120)

LLC taxed as C-Corp — Federal: October 15 | NY: October 15 | FL: 6 months from original due (Form F-1120)

Single-Member LLC / Sole Proprietor — Federal: October 15 | NY: October 15 (NYC UBT: Form NYC-204 due October 15) | FL: N/A

Documents You Need Before Filing an Extended Return

A CPA can only file an accurate return with accurate records. Business owners who come in without the right documents either delay the filing or risk errors that cost more to fix later. Here is exactly what to have ready before that conversation happens.

Income and Revenue Records

The first document on your list should be the profit and loss statement for the year. Without it, there is no clear picture of what the business earned or spent, and the return cannot be filed accurately. The second is a balance sheet dated the last day of your year. Bank statements and 1099s issued to contractors or received from clients are also important for filing. These three items alone resolve most of the income-side questions a CPA will ask. If you do not have these forms ready, we can provide bookkeeping services to provide them for you.

Payroll and Tax Payment Records

Payroll records and all filed 941s for the year need to be in one place before filing. The 941 is the quarterly federal tax return employers file to report wages paid and taxes withheld, and you will need every quarter accounted for. Records of any estimated tax payments made during the year also matter here. A copy of the prior year return rounds this out and gives you a baseline to compare against.

Entity-Specific Records

This is where the document list changes depending on the business structure. S-Corp filers need to bring shareholder basis information, which tracks each shareholder’s investment in the company and determines how distributions and losses are handled on the return. Partnership filers need partner capital account records for the same reason. Business owners in New York City also need records of any payments made toward the Unincorporated Business Tax or the General Corporation Tax. Missing any of these slows the filing down significantly.

What Happens When the Books Are Not Ready Before the Deadline

Arriving at a CPA’s office with months of unreconciled books has a predictable outcome, and it is an expensive one. A missed October 15 deadline carries a late-filing penalty of 5 percent of unpaid tax per month, up to 25 percent, and that amount sits on top of the interest that has been accruing since April. Books that are three or more months behind take weeks to sort out properly. Queens business owners with NYC Commercial Rent Tax obligations have an extra layer on top of that, since those records need to be handled separately, and missing that paperwork holds up the entire filing.

How ETCPA Handles Extended Business Returns

ETCPA has been filing business tax returns for clients in Queens and New York City since 1993. When a business owner reaches out, the first step is a straight review of what has been filed, what is still owed, and whether the books are ready. From there, the return is completed on a timeline that accommodates the deadline.

The firm serves clients in both English and Spanish, so Queens business owners who prefer to work in Spanish do not need to look elsewhere. ETCPA is available year-round, and business owners who call in July or August reach the same CPA they would in March, not a call center.

There are two offices, one in Forest Hills and one in Midtown Manhattan, both handling extended returns for LLCs, S-Corps, partnerships, and C-Corps across New York and Florida.

Who This Applies To

• LLC owners in New York and Florida with a federal extension still open
• S-Corp and partnership filers with a September 15 deadline approaching
• C-Corp filers working toward the October 15 deadline
• Business owners who have not yet made estimated tax payments this year
• Anyone whose books are behind and who is not sure if the return can be filed accurately by the deadline
• Spanish-speaking business owners in Queens looking for a bilingual CPA who handles extended returns

The Extension Bought Time. Here Is How to Use What Is Left.

October 15 is a hard stop, and there is no extension after that. Business owners in New York and Florida who still have an open return, unresolved books, or unpaid estimated tax have enough time to get this done correctly if they move now.

ETCPA handles extended business returns year-round from Forest Hills and Midtown Manhattan. Business owners facing an approaching deadline, with unreconciled books, or questions about what is still owed can call 718-261-9600 or email file@etcpa.com. A brief conversation is usually enough to determine exactly where things stand and what needs to happen before the deadline.