Learning Center
We keep you up to date on the latest tax changes and news in the industry.

Essential September 2025 Tax Deadlines for Businesses

As we approach the tax deadlines in September 2025, it's crucial for businesses to be well-prepared. Key dates include the final filing for S corporations and partnerships with extensions, corporate estimated tax payments, and payroll tax deposits all due by September 15. Staying organized and compliant will ensure a smooth transition into year-end planning.

September 15 - S Corporations
For S corporations, it's time to file your 2024 calendar year income tax return (Form 1120-S) and settle any outstanding tax obligations. This deadline applies if an automatic six-month extension was previously secured. Shareholders should receive their Schedule K-1 (Form 1120-S) or an equivalent Schedule K-1, along with Schedule K-3 (Form 1120-S) if applicable.

Financial Planning

September 15 - Corporations
Corporations should not overlook the requirement to deposit the third installment of estimated income tax for the current fiscal year.

September 15 - Partnerships
Partnerships also face their deadline for the 2024 calendar year return (Form 1065), provided a six-month extension was granted earlier. It’s essential for each partner to receive their Schedule K-1 (Form 1065) or a substitute, and Schedule K-3 (Form 1065) when necessary.

Schedule a Complimentary Consultation
Choose from our locations and meet with one of our qualified staff members. If you prefer to secure a Virtual Meeting via Zoom or Phone, please contact our offices at 877.908.1040
Schedule Here

Notary Seal

September 15 - Social Security, Medicare, and Withheld Income Tax
If monthly deposit rules apply to you as an employer, ensure that deposits for Social Security, Medicare, and withheld income tax are completed for August 2025. These rules similarly apply to nonpayroll withholding.

Weekends & Holidays:
If any deadline falls on a non-business day, such as weekends or public holidays, it automatically shifts to the subsequent business day.

Disaster Area Extensions:
In cases where regions have been identified as disaster areas, filing deadlines may be extended. To verify whether this applies and to obtain specific extension dates, consult the following resources:
FEMA: Disaster Declarations
IRS: Tax Relief

Schedule a Complimentary Consultation
Choose from our locations and meet with one of our qualified staff members. If you prefer to secure a Virtual Meeting via Zoom or Phone, please contact our offices at 877.908.1040
Schedule Here
Share this article...

Want tax & accounting tips and insights?

Sign up for our newsletter.

I confirm this is a service inquiry and not an advertising message or solicitation. By clicking “Submit”, I acknowledge and agree to the creation of an account and to the and .

TAX DRx at a Glance

Our expertise is widespread and we have multiple office locations to make it convenient for you to get help. You can find us at:

TAX DRx Corporate Headquarters

502 Centennial Ave
Cranford, NJ 07016
(Grd St Pkwy - Ext 136)
(877) 263-1041

NYC - Harlem Franchise Office

2123 Frederick Douglass Blvd
New York, NY 10026
(8th Ave & 115th St.)
(Subway B, C, Bus M3)
(877) 263-1041

TAX DRx - Hillside

*Charles Dort, Managing Partner*
1568 Maple Ave, Store #1
Hillside, NJ 07205
(Corner of Conklin Ave)
(877) 408-1048

TAX DRx, dba/ TaxJohn

TaxJohn Tax Services
121 Park Ave
Plainfield, NJ 07060