April 15 is less than two weeks away, and if you own a small business, there is a good chance your to-do list is already overflowing. Between running day-to-day operations, managing employees, and keeping customers happy, tax filing often gets pushed to the last minute. But missing this deadline, or filing without the right information, can cost you real money in penalties, interest, and missed deductions.
Use this checklist before April 15, 2026 if you file yourself, work with a CPA, or still need to organize your books. It covers federal and state deadlines, estimated payments, common deductions, and the documents to have ready.
What Is Due on April 15, 2026?
April 15 is more than one deadline. It is several stacked on top of each other. Here is what the IRS expects from small business owners by this date:
- Individual tax returns (Form 1040). If you are a sole proprietor, single-member LLC, or report business income on your personal return, this is your filing deadline.
- C-Corporation tax returns (Form 1120). Calendar-year C-Corps generally must file Form 1120 by this date.
- Q1 2026 estimated tax payment. Your first quarterly estimated tax payment for the current tax year is due on the same day.
- IRA and Roth IRA contributions for 2025. This is your last chance to make contributions to an IRA or Roth IRA that count toward the 2025 tax year.
- Trust and estate returns (Form 1041). If you manage a trust or estate with a calendar year-end, this return is also due April 15.
If your business is an S-Corporation or partnership, your return was already due on March 15. If you missed that deadline and did not file an extension, you may already be accruing penalties. Contact DeMar Consulting Group if you need help catching up.
Step 1: Gather Your Tax Documents
The single biggest reason small business owners file late is missing documents. Start collecting these now if you have not already:
Income Documents
- 1099-NEC forms (for contract income over $600)
- 1099-K forms from payment processors, payment apps, or online marketplaces. Card processors may issue these regardless of amount; third-party settlement organizations generally must issue them when goods-or-services payments exceed the IRS reporting threshold.
- 1099-INT and 1099-DIV (interest and dividend income from business accounts)
- Year-end profit and loss statement from your accounting software
- Sales records, invoices, and any cash income logs
Expense Documents
- Bank and credit card statements for all business accounts
- Receipts for major purchases (equipment, software, office supplies)
- Vehicle mileage log (if you deduct business driving at 70 cents per mile for 2025)
- Home office measurements (if you claim the home office deduction)
- Health insurance premium statements (Form 1095-A, 1095-B, or 1095-C)
- Retirement plan contribution records (SEP IRA, Solo 401(k), SIMPLE IRA)
- Loan interest statements (Form 1098 for mortgage, business loan statements)
Payroll Documents (If You Have Employees)
- W-2s issued to employees
- 1099-NEC forms issued to contractors
- Quarterly payroll tax returns (Form 941)
- State payroll tax filings
- Workers’ compensation records
If you use bookkeeping services or QuickBooks Online, pull these reports directly from your software. Reconcile your books through December 31, 2025 before your CPA starts the return.
Step 2: Review Your Deductions Before Filing
This is where most small business owners leave money on the table. Before you or your CPA hit “submit,” confirm that your return captures every deduction you can support. Here are the ones most commonly missed:
Home Office Deduction
If you use a dedicated space in your home regularly and exclusively for business, you can deduct it. The simplified method allows $5 per square foot, up to 300 square feet for a $1,500 maximum. The regular method lets you deduct actual expenses based on the percentage of your home used for business. Many small business owners skip this deduction because they think it triggers audits. It does not, as long as you qualify.
Vehicle and Mileage Deduction
You can deduct business mileage at 70 cents per mile for 2025, or you can deduct actual vehicle expenses (gas, insurance, repairs, depreciation) based on the business-use percentage. You need a mileage log either way. Apps like MileIQ or a spreadsheet work fine because the IRS needs date, destination, purpose, and miles driven.
Qualified Business Income (QBI) Deduction
Pass-through owners, including sole proprietors, LLC members, S-Corp owners, and partners, may qualify for a deduction of up to 20% of qualified business income under Section 199A. The One Big Beautiful Bill Act made the deduction permanent. Income limits and phase-outs apply for certain service businesses, so check with your CPA if you are near the threshold.
Retirement Contributions
You still have until April 15 to make certain retirement contributions for the 2025 tax year. SEP IRA contributions can be as high as 25% of eligible compensation, subject to the $70,000 2025 limit. You can contribute up to $7,000 to a Traditional IRA, or $8,000 if you are 50 or older. Your deduction depends on income, filing status, and whether you or your spouse participate in a workplace retirement plan. These can be one of the most powerful tax planning strategies available to small business owners.
Other Commonly Missed Deductions
- Software subscriptions like QuickBooks, Slack, Zoom, project management tools, and any SaaS you use for business are deductible.
- Professional development including courses, certifications, conferences, and business books.
- Business insurance premiums such as general liability, professional liability, cyber insurance.
- Self-employed health insurance. If you are not eligible for an employer plan, you can deduct 100% of your premiums.
- Cell phone and internet. The business-use percentage of your phone bill and internet service.
Step 3: Make Your Q1 2026 Estimated Payment
This is the one that catches people off guard. While you focus on filing last year’s return, remember that the IRS also expects your first estimated payment for the current year on the same day. If you owed more than $1,000 last year and expect a similar bill this year, plan on quarterly estimated payments.
The four quarterly due dates for 2026 are:
- Q1: April 15, 2026
- Q2: June 15, 2026
- Q3: September 15, 2026
- Q4: January 15, 2027
A common safe-harbor approach is to pay at least 100% of last year’s tax liability spread across four equal payments, or 110% if your adjusted gross income was over $150,000. That can help you avoid an underpayment penalty even if your final tax bill is higher than expected.
Step 4: Decide Whether to File or Extend
If your documents are not ready or you need more time, filing an extension is not a bad thing. Form 4868 gives you until October 15 to file your return. But there is a critical catch: an extension to file is not an extension to pay. You still need to estimate what you owe and pay it by April 15 to avoid interest and penalties.
Filing an extension makes sense when:
- You are waiting on a K-1 from a partnership or S-Corp
- You had a complex tax year (sold property, started a new business, moved states)
- Your books are not reconciled and you need more time to get accurate numbers
- You want your CPA to have enough time to review the return and find supported savings instead of rushing
Filing an extension does not increase your audit risk. The IRS does not penalize you for extending as long as you pay on time.
Step 5: Avoid These Last-Minute Mistakes
Tax season pressure leads to rushed decisions. Watch out for these common errors:
- Mixing personal and business expenses. If your books are not clean, you may be missing deductions or accidentally claiming personal expenses. Clean books are the foundation of an accurate return.
- Forgetting state filing requirements. If you earned income in multiple states or have employees in other states, you may need to file state returns beyond your home state.
- Not reconciling your bank accounts. Your profit and loss statement only works if you reconcile bank accounts through year-end. Unreconciled accounts can hide income or duplicate expenses.
- Ignoring the SALT deduction changes. The One Big Beautiful Bill increased the SALT cap to $40,000 for 2025 and indexes it higher for 2026. If you were not itemizing before because of the old $10,000 cap, it may now be worth revisiting.
- Not keeping records. The IRS requires you to keep tax records for at least three years from the date you filed, or two years from the date you paid the tax, whichever is later. For certain items like property records, keep them for as long as you own the asset plus three years.
Your April 15 Tax Checklist (Quick Reference)
- All income documents collected (1099s, bank statements, sales records)
- All expense documentation organized (receipts, mileage logs, statements)
- Books reconciled through December 31, 2025
- Home office deduction calculated (if applicable)
- Vehicle mileage log finalized
- QBI deduction eligibility confirmed
- Retirement contributions made (SEP IRA, Traditional IRA deadline is April 15)
- Q1 2026 estimated tax payment calculated and ready to submit
- Extension filed (Form 4868) if you need more time
- Payment submitted even if extending (extension to file is not extension to pay)
- State filing requirements reviewed
- Prior year return reviewed for carryforward items
Frequently Asked Questions About the April 15 Tax Deadline
What Happens If I Miss the April 15 Deadline?
If you miss the April 15 filing deadline without an extension, the IRS charges a failure-to-file penalty of 5% of your unpaid taxes per month, up to 25%. If you filed an extension but did not pay, you face a failure-to-pay penalty of 0.5% per month plus interest. Filing late without an extension is significantly more expensive than extending and paying on time, so always file the extension if you are not ready.
Can I Still Make Retirement Contributions for Last Year?
Yes. April 15 is the deadline for Traditional IRA and Roth IRA contributions for the prior tax year. For 2025, you can contribute up to $7,000 ($8,000 if age 50 or older). SEP IRA contributions can generally be made until your filing deadline, including extensions. If you extend to October 15, you may have until then to make the SEP contribution. Solo 401(k) employee deferrals generally needed a year-end election, but employers may make employer contributions by the filing deadline.
Do I Need to Make Estimated Tax Payments?
You generally need to make estimated tax payments if you expect to owe $1,000 or more in federal tax for the year after subtracting withholding and credits. This applies to most self-employed individuals, freelancers, and business owners who receive income without tax withholding. The first quarterly payment for 2026 is due April 15, the same day as your 2025 return.
Should I File an Extension or Rush to File by April 15?
If your books are clean and your documents are ready, file on time. But if you are missing K-1s, have unreconciled accounts, or had a complicated year, extending is the smarter choice. A rushed return with errors can trigger IRS notices and potentially cost more in missed deductions than taking extra time to get it right. The extension is free and gives you until October 15.
What Is the Penalty for Not Paying Estimated Taxes?
The IRS charges an underpayment penalty if you did not pay enough tax throughout the year through withholding or estimated payments. The IRS calculates the penalty quarterly using the federal short-term interest rate plus 3 percentage points. To avoid the penalty, pay at least 100% of last year’s tax liability across four equal payments, or 110% if your adjusted gross income exceeded $150,000.
Sources and Filing References
- IRS: When to file individual tax returns
- IRS Publication 509: Tax Calendars
- IRS: Understanding Form 1099-K
- IRS: Standard mileage rates
- IRS: Retirement plan contribution limits
How DeMar Consulting Group Can Help
If April 15 is approaching and you are not ready, you are not alone. Many small business owners wait until the last minute because they are busy running their business. That is exactly what DeMar Consulting Group is here for. Our team of CPAs works with small businesses and startups across the United States to prepare accurate returns, maximize deductions, and ensure you never pay more than you owe.
Whether you need last-minute filing help, want to set up quarterly estimated payments, or are looking for a CPA firm that understands small businesses, schedule a free consultation with DeMar Consulting Group today. We can help you cover April 15 and the deadlines that follow.
