Quarterly estimated-tax deadlines have a way of showing up quickly.

One minute, you’re focused on serving clients, shipping orders, or keeping up with the normal demands of your business. Then, suddenly, your next estimated payment is due, and you’re trying to figure out whether your books are current enough for your CPA to calculate it.

Quarterly estimated taxes for small business owners don’t have to create a last-minute scramble. With current bookkeeping and a simple routine, you can give your CPA better information and feel more prepared when each deadline arrives.

What Are Quarterly Estimated Taxes?

The United States has a pay-as-you-go tax system. That means taxes generally need to be paid as income is earned instead of waiting until you file your annual return.

Employees usually handle this through taxes withheld from their paychecks. However, business owners may need to make estimated payments because taxes aren’t automatically withheld from their business income.

According to the IRS guidance on estimated taxes, sole proprietors, partners, and S corporation shareholders generally need to make estimated payments if they expect to owe $1,000 or more when filing their return. Different rules and thresholds can apply depending on your situation and business structure.

For 2026, the third estimated-tax payment is due September 15. Still, your CPA or tax professional should determine whether you need to pay, how much you owe, and which deadlines apply to you.

Your bookkeeper’s role is different. We make sure the financial information used for those decisions is organized, current, and accurate.

How to Prepare for Quarterly Estimated Taxes as a Small Business Owner

1. Bring Your Bookkeeping Up to Date

Before your CPA can estimate your income for the year, they need to know how your business has performed so far.

First, make sure all business income and expenses have been entered into your bookkeeping system. If you sell through multiple platforms or receive payouts after fees are removed, confirm that your full sales activity is being recorded, not only the deposits that reach your bank account.

For example, a Whatnot seller may receive a $700 deposit after platform fees, refunds, and other adjustments. However, that deposit alone doesn’t show the full amount of sales or expenses that occurred. Recording those pieces correctly gives your CPA a much clearer picture.

If your financial system needs some attention, start with these seven steps for organizing your small business finances.

2. Reconcile Every Business Account

Next, reconcile each business checking account, credit card, savings account, and loan account through the most recent statement.

Reconciliation confirms that the activity in your bookkeeping system matches the activity reported by your financial institution. It can uncover duplicated transactions, missing expenses, incorrect balances, or payments recorded in the wrong account.

Simply connecting your bank feed to QuickBooks doesn’t mean your accounts are reconciled. Someone still needs to review the activity and confirm that everything matches.

3. Review Your Profit and Loss Statement

Once your accounts are reconciled, review your profit and loss statement. This report shows your business income, expenses, and net profit for a specific period.

Your CPA may use this information when helping you plan for estimated taxes. Therefore, take a moment to check the report for anything that looks unusual.

Ask yourself:

• Does the income look reasonable based on my sales?
• Are any expense categories unusually high or low?
• Are large purchases recorded correctly?
• Are there vague categories such as “Other Expense” that need review?
• Does anything appear to be missing?

If you aren’t comfortable reading this report yet, our guide to understanding your profit and loss statement explains what each section means.

4. Tell Your CPA About Significant Changes

Your business may look very different from when your last estimated payment was calculated.

Perhaps your revenue increased, you lost a large client, hired an employee, purchased equipment, changed your business structure, or started earning money through a new income stream. Personal changes may also affect your tax situation.

As a result, your CPA needs more than a copy of last year’s tax return. Let them know about any meaningful business or personal changes so they can determine whether your previous estimate still makes sense.

5. Keep Tax Money Separate

If tax deadlines repeatedly leave you wondering where the money will come from, consider creating a separate business savings account for taxes.

Then, move money into it consistently instead of waiting until a payment is due. Your CPA can help you determine an appropriate amount or percentage based on your specific tax situation.

Separating the money also makes it easier to see what is truly available for operating expenses, owner pay, and future business plans.

What If Your Bookkeeping Is Behind?

If your bookkeeping isn’t current, don’t ignore the deadline because you feel embarrassed about the state of your books.

Instead, gather what you have and contact your bookkeeper and CPA as soon as possible. Let them know how far behind the records are and ask what information is most urgent.

Getting caught up may take some work. However, waiting usually makes the process harder, especially as year-end gets closer.

Better Bookkeeping Makes Tax Planning Easier

Quarterly estimated taxes for small business owners are ultimately a tax-planning responsibility, but accurate bookkeeping provides the information that planning depends on.

When your accounts are reconciled and your reports are current, you don’t have to recreate months of financial activity every time a deadline approaches. Instead, you can send reliable information to your CPA and get back to running your business.

If your books are behind or you’re tired of preparing for every tax deadline at the last minute, explore our monthly bookkeeping services. You can also schedule a free 15-minute discovery call with me to see whether Ever Leslie Bookkeeping is the right fit for your business.

Ever Leslie Bookkeeping provides bookkeeping and financial-organization services. We are not CPAs and do not provide tax advice or file income-tax returns. This information is educational and should not replace guidance from a licensed CPA or tax professional.