The seven costliest mistakes new U.S. business owners make are getting the EIN wrong, assuming the default tax treatment fits, mixing personal and business money, missing state filings and registered agent requirements, overlooking Form 5472 as a foreign owner, skipping estimated taxes, and filing a report that no longer applies. An LLC compliance checklist tied to actual dates is the simplest way to catch each one before a deadline passes.
Setting up a business the right way the first time isn’t the issue for new entrepreneurs in the U.S. Most new businesses simply make one or more of the mistakes listed below. These are some of the easy-to-avoid filing and setup issues that pop up for new businesses. They cover the EIN, tax classification, banking, state filings, Form 5472, estimated taxes, and reporting rules. A simple LLC compliance checklist tied to actual dates solves the problem.
Why a New LLC Needs a Dated Compliance Checklist
Setting up an LLC in a state only requires one filing. But staying compliant with the IRS and the state requires a calendar. And sometimes a third state where you operate also requires compliance. Each year, the IRS, the state where you formed your LLC, and perhaps another state expect that your LLC file an annual report. The penalty for missing a filing is usually greater than the cost of the filing.
This LLC Compliance Checklist outlines seven of the most common mistakes new businesses make, along with the forms and deadlines tied to October 2026.
1. EIN Errors: Mismatched Entity Type and Responsible Party
If you are the responsible party for your LLC and you have a Social Security number or an ITIN, you can apply for an EIN. If you do not have an SSN or an ITIN, you are considered a foreign individual and need to do additional research to find out the steps to getting an EIN from the IRS.
The IRS usually takes a few days to process the EIN, and you should keep the confirmation letter the IRS sent you for your records. Some banks require a copy of this letter when opening a business bank account, and others may not.
Mistakes usually happen in the details. An EIN may be issued to a different entity type than the state in which the LLC was formed, or a different responsible party may be listed. Banks reject the application, and the IRS sends a letter to an entity that no one is even familiar with.
2. Tax Classification: When Default LLC Treatment Costs You Money
Generally speaking, single-member LLCs are taxed as disregarded entities, and profit flows to the owner personally. Multi-member LLCs are taxed like partnerships and are required to file Form 1065 by March 15, with a Schedule K-1 for each member.
Neither tax treatment is always best for a business. Some owners elect S corporation status by filing Form 2553. This form generally has to be filed within two months and 15 days of the tax year in which the election is being made. Missing this window means the LLC retains default tax treatment for that year. The cost of this default treatment is also reported on the owner’s personal tax return as self-employment income, taxed at 15.3% of net income.
Keep in mind that an S corporation election also means the business is subject to payroll taxes and requirements, so be sure to check with a tax professional to see if this is the most cost-effective treatment for your business.
3. Commingled Funds: How Mixing Personal and Business Money Weakens Your LLC
Mixing personal and business money usually begins with paying business expenses with personal money. While this may seem like an easy way to conduct business, it turns bookkeeping into a guessing game and, over time, defeats the purpose of having an LLC.
Courts in many states consider whether a business owner has commingled their personal and business funds when deciding whether to impose personal liability for the business’s debts. Again, this is ruled on a state-by-state basis, and the best defense to this is usually a clean paper trail.
The IRS usually looks for business tax records for at least 3 years from the date the return was filed, so keep your tax records for that long.
4. State Filings and Registered Agents: Fees, Deadlines and Good Standing
State regulations are the most varied part of the checklist.
- Delaware charges LLCs an annual tax of $300, due on June 1.
- California requires an LLC to pay an $800 minimum annual franchise tax and also to file a Statement of Information.
- Texas requires an annual franchise tax report, due May 15, even if no tax is due.
Always confirm with the Secretary of State or the tax agency in your state for the latest and correct amount and due date.
Late fees are the least of your worries. Missing state filings can cause you to lose your “good standing” status with the state or even lead to an “administrative dissolution.”
The registered agent is the second part of the trap. A registered agent must be physically present in the state and have a valid street address. If the registered agent leaves or the address becomes stale, a notice of a lawsuit can become a default judgment.
Owners of businesses with multiple entities across various states typically use a service to ensure they remain in good standing, so no one person has to remember all the deadlines.
5. Form 5472: The $25,000 Penalty for Foreign-Owned LLCs
This is the most costly error. A single-member U.S. LLC with a foreign owner must file Form 5472 and report income on a pro forma Form 1120 even if there is no income. A capital contribution is treated as a reportable event, so the first year is usually covered.
The failure-to-file penalty is $25,000 for each Form 5472 not filed. The due date for a calendar-year LLC is April 15, and Form 7004 extends the filing to October 15.
In most cases, no tax is due, so founders often overlook it. Confirm the current filing method for this form in the IRS instructions for Form 5472.
6. Estimated Taxes: Quarterly Form 1040-ES Payments for LLC Owners
LLC profits are not subject to payroll tax withholding, so quarterly payments to the IRS via Form 1040-ES are expected. Payments are due on April 15, June 15, September 15, and January 15 of the following year. A shortfall triggers a penalty.
Someone who makes $60,000 in the first year, for example, and pays nothing until April would owe the tax due, plus a penalty. A better way to manage this is to stash a portion of each paycheck in a tax savings account.
Non-resident owners of a U.S. business follow different forms, including Form 1040-NR. So, determine which rules pertain to your residency status.
7. BOI Reporting: Why U.S. Companies No Longer File Under the Corporate Transparency Act
The topic of 2024 and 2025 was the reporting of Beneficial Ownership Information (BOI). As of August 14, 2026, the Final Rule of the Corporate Transparency Act permanently exempts U.S. entities and persons. U.S. state-registered entities of foreign origin may still have a reporting obligation.
In 2026, many filing services charged owners a fee to complete BOI reports. Depending on your entity type, you may not have had to file a BOI report. Check FinCEN’s BOI page to ensure you’re not paying to file a report you don’t need to file.
LLC Compliance Checklist: Eight Items to Confirm Before Each Deadline
- EIN confirmation letter saved and corresponding state records
- Tax classification confirmed, with noted deadlines for Forms 2553 or 8832 as relevant
- Business bank account opened, with no personal expenses
- State annual report and franchise tax due dates in the same calendar year
- Registered agent, with service of process address as filed
- Scheduled Form 5472 and Pro Forma 1120 for single-member foreign-owned LLCs
- Set up quarterly estimated tax payments for April, June, September, and January
- Checked BOI status against FinCEN’s recent rule
Your Next Step: A Ten-Minute Good Standing Check
- Select the three most applicable dates from this list, add them to a calendar, and set reminders for yourself two weeks in advance.
- Next, log in to your state’s Secretary of State website and confirm that your business exists and is in good standing.
This ten-minute exercise catches most issues while it is still inexpensive to address.