Here at Go Curry Cracker we talk a lot about paying zero taxes. It’s a fun little game that you win just by playing.

But it won’t happen every year, probably. And in the years you owe tax, come April the IRS will penalize you and charge back interest if you haven’t paid enough in advance – either through paycheck withholding or estimated taxes (or both.)

This is how you avoid that bit of unpleasantness.

Avoid Tax Penalties

Tax penalties are applied whenever you fail to pay enough taxes along the way / as the income is earned. For W2 workers, this happens through your employer. For self-employed people, we pay estimated taxes quarterly – both income taxes and self-employment taxes.

Underpayment usually happens from:

W2 employee under-withholding – either you miscalculate exemptions on a W4 or inappropriately claim to be “Exempt”

Self-employed – fail to make appropriate quarterly estimated tax payments. Be sure to include SE taxes (use our SE tax calculator.)

Travel hacker extraordinaire – sometimes people intentionally withhold too little on their W2 job and then make estimated tax payments on the side in order to meet credit card minimum spend requirements. Don’t forget. (I used to do this which is how we we got a free honeymoon in Hawaii.)

Substantial investment income – any of the above but neglecting to include dividend and capital gain income

Safe Harbor Rules

Pay enough tax throughout the year and you will never encounter a tax penalty. But how much is enough?

The IRS provides some safe harbor rules to make this crystal clear:

Rule 1 – pay at least 100% of the tax you owed last year
(or if AGI is more than $150,000 MFJ, pay 110% of what you paid last year.)

For example, in 2020 we paid $4,891 in combined taxes (income and self-employment.) As long as we pay at least $4,891 in estimated taxes this year, we will be fine. Or if AGI is expected to exceed $150k, pay an extra $500.

Rule 2 – pay at least 90% of what you will owe this year

Maybe last year was a big income year and this year you earned much less. In that case, base estimated taxes / withholding on current year income.

Our tax calculator can help with making an estimate. (Designed for tax hackers and early retirees!)

Rule 3 – Be within $1,000 of your total tax burden

If total tax burden for the year is estimated to be $1,001, pay at least $1 up front.

In all cases, you then true up when you file your tax return in April.

Estimated Taxes

As with all things from the IRS, there are rules for estimated taxes. They need to be paid on time and on schedule.

Estimated taxes are due “quarterly” – April 15th, June 15th, September 15th, and January 15th of the following year.
(One of these quarters is 4 months and another is 2, which makes perfect sense…)

If income is lumpy you can calculate as you go, attributing tax to the respective quarter the income was earned. Or you can just estimate for the entire year and pay an equal amount 4 times.

You can use Form 1040-ES (pdf) to make the appropriate estimation.

You can pay by check via mail. You can pay electronically. You can pay by credit card. Details.

I almost always pay by credit card even though it comes with a small fee. As a small business owner, paying my self-employment taxes this way is a deductible expense. And since I’m typically doing this with new credit cards, I’m ok paying $50 in fees to get $500+ in future travel.

Hot tip – you can also apply last year’s refund to this year’s estimated taxes, which could be in lieu of the April payment.

An example of avoiding tax penalties

You make $50k/year as a W2 employee and have your withholding dialed in perfectly.

Then you sell a bunch of stock, realizing a capital gain of $250,000 because you want to buy a house or a sweet boat. Per our tax calculator, for MFJ in 2021 this will result in tax on investment income of ~$36,500 (+NIIT, ignored for simplicity.)

Do you need to do anything?

Clearly the expected withholding from the paycheck will NOT get us to within $1,000 of taxes due for the year.

Do we need to then pay estimated taxes?

Since total AGI will be over $150k, we need to insure we have pre-paid at least 110% of what was owed last year. On the same income in 2020 that would be $2,629 in tax. 110% of that is $2,892.

Option A – make an estimate tax payment of $300 and set aside $36,500 to pay in April.
Option B – increase paycheck withholding by $300 for rest of year and set aside $36,500.
Option C – make an estimated tax payment of $36,500 this quarter because it is convenient to do so
Option D – do nothing

If we do nothing then we are liable for interest and penalties.

Interest is typically the federal short-term interest rate (currently 0%) plus 3%. Today that total is 3%.

Penalties can be harsh – 0.5% per month or partial month, from the date it is due until the date it is paid in full. If our hypothetical tax sale took place in January and we filed in April, that is 16 months of interest (8%.)

Since we don’t meet any of the safe harbor requirements, we are looking at paying another ~10% of the $36,500 tax due, or $4k+/-.

Summary

It is pretty easy to avoid tax penalties for underpayment of taxes. Just follow the safe harbor rules and pay quarterly.

If you have a big income windfall, make an estimated tax payment. This works even if you are W2.

If you are going to pay taxes, be sure to get a free-ish vacation out of it.

Have you ever been hit by a tax penalty?