The California $1 Million Estimated-Tax Trap: Why Proactive Tax Planning Matters

Did you get hit with an underpayment penalty and interest on your most recent tax return?

That is never fun. It is especially painful when the penalty could have been reduced or avoided with proactive tax planning and properly timed payments.

You may have heard that taxes are due by the tax filing deadline. You may also know that filing an extension gives you more time to file, but not more time to pay.

Both statements are true.

But what if the IRS or California expected you to make payments throughout the year?

Paying your entire balance when you file your return may not protect you from a penalty if you were required to make estimated tax payments earlier.

This may come as a surprise on your next tax return. Over the past few years, many California taxpayers living in designated fire, flood, and winter storm disaster areas received additional time to make certain estimated tax payments. If you qualified for that relief, the normal payment schedule may not have affected you in the same way.

As those disaster postponements expire, the regular estimated tax deadlines apply again. Taxpayers who became accustomed to paying later could unexpectedly face an underpayment penalty on their next return.

Who Needs to Make Estimated Tax Payments?

Most people associate quarterly tax payments with business owners.

That makes sense. Business owners and self-employed individuals often earn income without having taxes withheld from it.

But estimated tax payments are not just for business owners.

...are you an employee who had a large amount of RSUs vest?
...did you exercise stock options?
...did you receive a substantial bonus?
...did you sell a business, investment property, or other asset?
...did you recognize a large capital gain?

Any of these events could increase your tax liability and create a need for additional withholding or estimated tax payments.

The IRS and California both provide SAFE HARBOR rules that may help you avoid an underpayment penalty. However, the federal and California rules are not identical.

California has an additional rule for taxpayers whose current year California adjusted gross income reaches $1 million. Missing this rule can become very expensive.

What Is an Estimated Tax Safe Harbor?

The federal and California tax systems operate on a pay-as-you-go basis.

That means you are generally expected to pay taxes as you earn income throughout the year. Those payments may be made through payroll withholding, estimated tax payments, or a combination of both.

What does Safe Harbor mean?

A Safe Harbor is the minimum amount you generally need to pay during the year to avoid an estimated tax underpayment penalty.

Does meeting the safe harbor mean you will not owe anything when you file?

No.

The safe harbor may protect you from an underpayment penalty, but it does not reduce your actual tax liability.

For example, assume your safe harbor payment is $50,000, but your final tax liability is $80,000. Paying the $50,000 safe harbor amount may help you avoid an underpayment penalty, but you could still owe the remaining $30,000 when you file your return.

How Does the Federal Safe Harbor Work?

For federal purposes, you can generally avoid an estimated tax penalty by paying at least the smaller of:

1. 90% of your current year federal tax

2. 100% of your prior year federal tax

3. 110% of your prior year federal tax if your Adjusted Gross Income was more than $150k

Here is an example.

Assume your federal tax last year was $40,000 and your prior year adjusted gross income was more than $150,000.

Your prior year safe harbor amount would generally be:

$40,000 × 110% = $44,000

Now assume your current year federal tax is expected to be $90,000.

Ninety percent of your current year tax would be:

$90,000 × 90% = $81,000

Because $44,000 is less than $81,000, you may be able to pay $44,000 during the year to satisfy the federal safe harbor.

You could still owe $46,000 when you file, but you may avoid an underpayment penalty if the $44,000 was paid properly and on time.

What happens if your income reaches $1 million?

For federal purposes, reaching $1 million does not eliminate the prior year safe harbor. Even at very high income levels, you can generally continue using 110% of your prior year federal tax if you otherwise qualify.

How Is California Different?

California begins with a similar calculation.

You generally pay the smaller of:

1. 90% of your current year California tax

2. 100% of your prior year California tax

If your prior year California adjusted gross income was more than $150,000, or more than $75,000 if married or a registered domestic partner filing separately, the prior year percentage generally increases to 110%.

So far, the rules sound similar, right?

Here is where California changes the game.

If your current year California adjusted gross income is $1 million or more, you generally lose the ability to use the prior year safe harbor.

The threshold is $500,000 if married or a registered domestic partner filing separately.

Once you reach this threshold, your California estimated tax requirement must generally be based on 90% of your actual current year California tax.

The key phrase is current year California adjusted gross income.

California is not looking at what you earned last year when applying the $1 million rule. California is looking at what you earn this year.

What Could the California $1 Million Rule Cost You?

Let’s walk through an example.

Assume your prior year California tax was $60,000 and your prior year California adjusted gross income was more than $150,000.

You might calculate your California safe harbor like this:

$60,000 × 110% = $66,000

At the beginning of the year, you plan to pay $66,000 and assume you are protected from an underpayment penalty.

Then your financial situation changes.

You sell a business, recognize a large capital gain, exercise stock options, or have a significant amount of RSUs vest.

Your current year California adjusted gross income increases to $1.2 million. Your current year California tax is now expected to be $150,000.

Can you still use the $66,000 prior year safe harbor?

Generally, no.

Because your current year California adjusted gross income reached at least $1 million, your required California payment would generally be based on 90% of your current year tax.

The calculation would look like this:

$150,000 × 90% = $135,000

You planned to pay $66,000, but California may expect you to pay $135,000 during the year.

That creates a potential safe harbor shortfall of:

$135,000 minus $66,000 = $69,000

Does that mean your penalty will be $69,000?

No. The $69,000 represents the potential shortfall in the amount California expected you to pay during the year.

However, that shortfall could generate substantial penalties and interest, especially if the required payments were due earlier in the year.

This is how a taxpayer can make the payments they thought were required and still end up with a painful California penalty.

California Also Has a Different Payment Schedule

The quarterly payment schedule is designed to make taxpayers fail.  At least, the IRS keeps it simple. Federal estimated tax payments are generally paid in four equaly installments of 25%.

California generally requires its annual estimated tax amount to be paid as follows:

1. 30% by April 15

2. 40% by June 15

3. 0% by September 15

4. 30% by January 15 of the following year

What does this mean for you?

California generally expects 70% of your required annual payment by June 15.

If you wait until September or December to review your tax situation, you may discover that an earlier California payment was already underpaid.

Can you simply make one large payment at the end of the year and fix everything?

Not necessarily.

A later payment may reduce the amount that remains unpaid, but it may not erase a penalty related to an earlier missed payment deadline.

How Does California Calculate the Penalty?

California calculates the underpayment penalty separately for each estimated tax deadline.

The amount is generally based on how much you underpaid, how long the balance remained unpaid, and the penalty rate in effect during that period.

For example, if you underpaid by $40,000 and it remained unpaid for 120 days at a 7% annual rate, the penalty would be approximately $921.

Making a larger payment later may stop additional penalties from accumulating, but it generally does not erase the penalty for an earlier missed deadline.

If your income arrived later in the year, such as from a business sale, RSU vesting, or a large capital gain, the annualized income method may help reduce the penalty by matching the required payments more closely to when the income was actually received.

Tax Preparation Looks Backward. Tax Planning Looks Forward.

What happens during traditional tax preparation?

Your tax professional gathers your information after the year ends, prepares the return, and calculates what you owe.

But by then, what has already happened?

...your income has already been earned
...your stock has already vested or been sold
...your business transaction has already closed
...your capital gain has already been recognized
...your estimated tax deadlines may have passed

Many valuable planning opportunities may be gone.

A proactive tax advisor does more than prepare a tax return. Your advisor helps you estimate what your upcoming return may look like before the year ends and, whenever possible, before a major transaction occurs.

We Will Handle It When We File ... Is Not a Tax Strategy

Can filing a correct tax return protect you from an estimated tax penalty?

Not always.

Your tax return reports what already happened. It cannot go back in time and correct payments that should have been made earlier in the year.

That is why estimated tax planning needs to happen before your return is filed.

Ideally, your tax projection should be updated throughout the year and whenever you experience a significant change in income.

The cost of proactive planning is often small compared with the potential cost of getting it wrong. A business sale, stock transaction, large bonus, or unexpected increase in income could create five figures or more in penalties and interest.

Proactive planning also gives you time to manage your cash flow. Instead of scrambling to make an unexpected payment, you can prepare for it in advance.

The Bottom Line

The federal and California estimated tax rules may look similar, but California’s $1 million rule creates a major difference.

The IRS generally continues to allow qualifying high-income taxpayers to use the prior year safe harbor.

California generally removes that option when current-year California adjusted gross income reaches $1 million. The threshold is $500,000 for married or registered domestic partner taxpayers filing separately.

What happens if you wait until your return is prepared to discover that you crossed the threshold?

It may be too late to avoid an underpayment penalty.

Working with a proactive tax advisor gives you the opportunity to estimate your upcoming tax return, adjust your payments before important deadlines pass, and prepare for major financial events before they become expensive surprises.

A tax return tells you what already happened.

Proactive tax planning helps you prepare for what happens next. That preparation could potentially save you five figures or more in avoidable penalties, interest, and costly mistakes.