Efficiently prepare your business tax return if you’re a business owner who filed for a tax extension earlier this year — your new filing deadline, September 15, 2025, is quickly approaching. For S Corporations, partnerships, and multi-member LLCs, this is the final call to get your Form 1120S or 1065 submitted without incurring IRS penalties.
Whether you’re a contractor, tradesman, or own a small service business, the key to filing a complete and accurate return on time is organization and proactive planning. Here’s a step-by-step guide to streamline the process, minimize errors, and avoid unnecessary costs.
Step 1: Know Your Entity Type and Filing Requirements
Before anything else, make sure you understand how your business is classified for tax purposes. This affects which forms you file and what deadlines apply.
- S Corporations: File Form 1120S
- Partnerships (including most multi-member LLCs): File Form 1065
- Single-member LLCs: Typically report income on Schedule C of the owner’s personal return (due April 15, not September 15)
Tip: If you’re unsure of your status, check your IRS approval letter (if you elected S Corp status) or consult with your CPA.
Step 2: Organize Your Financial Records
Gather and review all your bookkeeping records for the 2024 tax year. This is the foundation of your return — messy records lead to mistakes, missed deductions, or even audits.
Make sure you have:
- Profit & Loss (P&L) statement
- Balance sheet
- Bank and credit card statements
- Payroll reports
- Loan or equipment financing documents
- Asset purchase/depreciation records
Tip: Reconcile all accounts through at least June or July 2025 to catch errors early. If you use software like QuickBooks or Xero, run reconciliations for all bank and credit card accounts.
Step 3: Verify Shareholder or Partner Information
For S Corps and partnerships, your tax return generates Schedule K-1s — documents that each owner needs for their personal taxes. Make sure your CPA has:
- Full legal names
- Correct Social Security numbers or EINs
- Ownership percentages
- Contributions/distributions made during the year
Tip: Mistakes here delay your partners’ personal filings and could trigger IRS notices.
Step 4: Review Major Transactions
Large purchases, equipment upgrades, vehicle acquisitions, or business loans? Be sure they’re reflected in your financials and flagged for your CPA. These can qualify for depreciation, bonus depreciation, or Section 179 deductions.
Examples:
- Work trucks or vans
- Construction tools or machinery
- Office improvements
- Business-use computers or software
Tip: If you financed any assets, provide loan documents and payment breakdowns so your CPA can handle the depreciation and interest deductions correctly.
Step 5: Prepare for Estimated Taxes and Q3 Payments
The Q3 estimated tax payment deadline is September 16, 2025 — just one day after the extended business filing deadline. If your business is showing higher-than-expected profits, your CPA may recommend submitting an estimated payment to avoid underpayment penalties.
Tip: Once your 2024 return is prepared, ask your CPA to project your 2025 liability so you can stay ahead.
Step 6: Schedule Time With Your CPA Early
Don’t wait until the week of the deadline to reach out. Many CPAs are juggling dozens of business returns in September — especially if they work with construction and service-based businesses.
By scheduling a check-in in late July or early August, you give your CPA:
- Time to review your books thoroughly
- Room to advise you on tax strategies
- A buffer for any last-minute documentation or signatures
Tip: Ask about strategies to reduce taxable income — such as retirement contributions, vehicle use, or home office deductions.
What Happens If You Wait?
Procrastinating on your business return can lead to:
- $245 per owner, per month in late filing penalties (up to 12 months)
- Delayed K-1s for shareholders or partners
- Inaccurate returns that trigger audits or IRS letters
- Missed deduction opportunities that cost you thousands
Filing late doesn’t just create stress — it can directly hurt your bottom line.
Make Tax Season Simple With James D. Miller CPA
At James D. Miller CPA, we help small businesses, contractors, and tradesmen keep tax filing simple and stress-free. We understand the unique challenges of seasonal work, equipment-heavy operations, and complex ownership structures.
When you work with us, we’ll help you:
- Organize and review your financials
- File accurate and timely returns
- Maximize deductions for your industry
- Avoid costly filing mistakes or penalties
Final Word
The best way to meet the September 15, 2025 business tax deadline isn’t to rush — it’s to prepare efficiently and early. Clean books, early communication, and a proactive CPA make all the difference.
Need help getting started?
Contact James D. Miller CPA today to schedule your tax review. Let’s make this your smoothest filing season yet.