What Are the Biggest Tax Mistakes People Make?

The word “taxes” is enough to make any business owner or high-income earner break a sweat. While most people worry about mathematical errors or forgetting to claim a charitable donation, the biggest tax mistakes rarely happen on the actual tax return.

Instead, the most expensive errors are made months before the filing deadline. They are mistakes of strategy, timing, and oversight. As the tax code continues to shift—especially with recent federal updates and California’s notorious non-conformity rules—what you don’t know can literally cost you tens of thousands of dollars.

At Herbert Financial, we audit new client tax returns every year, and we see the exact same patterns of lost capital. If you want to stop leaving a “tip” for the IRS and the Franchise Tax Board, here are the biggest tax mistakes people make and how to avoid them.

1. Confusing Tax Preparation With Tax Planning

This is, without a doubt, the single most expensive mistake successful individuals make.

You hand your CPA your financial documents in March, they plug the numbers into their software, and they tell you what you owe. This is tax preparation. It is completely reactive. You are simply reporting historical data to the government.

True tax planning orange county business owners rely on is completely proactive. It happens in October or November. A strategic advisor looks at your current revenue, upcoming capital expenditures, and potential entity shifts to implement legal tax mitigation strategies before December 31st. If your accountant only speaks to you in the spring, you are missing out on aggressive, wealth-building deductions.

2. Ignoring California’s “Non-Conformity” Rules

If you live in California, the federal tax code is only half your battle. California is famous for “decoupling” or not conforming to many federal tax benefits.

For example, the federal government offers the 20% Qualified Business Income (QBI) deduction, which is a massive win for LLCs and S-Corps. However, California does not conform to QBI. This means your California taxable income is often much higher than your federal taxable income.

A skilled tax advisor orange county professionals trust will help you coordinate your strategy around this painful mismatch. They might recommend adjusting your payroll, maximizing state-specific R&D credits, or aggressively funding a Cash Balance Plan to pull your California taxable income down.

3. Missing the Pass-Through Entity (PTE) Tax Election

Speaking of California-specific headaches, the federal government capped the State and Local Tax (SALT) deduction at $10,000. For high earners in Southern California, your state income and property taxes blow past this limit instantly, resulting in double taxation.

To combat this, California introduced the Pass-Through Entity (PTE) tax election. This allows qualifying business owners to pay their state taxes at the entity level, effectively bypassing the federal SALT cap and creating a massive federal deduction. We consistently see new clients whose previous accountants simply forgot or didn’t know how to implement the PTE election, costing them tens of thousands in lost deductions.

4. Poor Income Timing

The IRS taxes income based on when you receive it. If you have a massive quarter and receive a large bonus or close a major real estate deal in December, it can push your entire year’s income into the highest possible tax bracket.

A high-level tax consultant orange county residents work with will actively manage your income timing. This might mean legally delaying the receipt of certain income until January of the next year, or accelerating your deductions (like pre-paying business expenses or executing a Donor Advised Fund contribution) into the current year to offset the spike in revenue. Timing is everything. If you are preparing to sell a highly appreciated asset, an advisor can guide you through options like a Deferred Sales Trust or a 1031 Exchange so you aren’t blindsided by a capital gains bill that wipes out your profit.

5. Operating Under the Wrong Business Entity

When you first started your business, a Sole Proprietorship or a basic LLC made perfect sense. But as your revenue scales past the six-figure mark, staying in that default entity structure is a massive mistake.

You end up paying the full 15.3% self-employment tax on every dollar of profit. By strategically transitioning to an S-Corporation, you can split your income into a “reasonable salary” and “shareholder distributions,” legally shielding a massive portion of your profits from self-employment taxes. Entity optimization is not a one-and-done event; it must be continually reviewed as your business grows.

Stop Paying the “Success Tax”

Mistakes happen, but when it comes to your wealth, strategic oversights compound rapidly. You cannot build a multi-million dollar net worth using standard, reactive tax strategies.

At Herbert Financial, we believe that proactive tax mitigation is the cornerstone of sustainable wealth. We do not just report your history; we engineer your financial future. We integrate your tax strategy directly with your overarching wealth management plan, ensuring you keep maximum capital exactly where it belongs: with you, your business, and your family.

Stop settling for basic preparation and start demanding elite strategy.