How to Slash Your Taxes: Tax Liability Estimation

With tax day fast approaching, most of us are in crunch mode to get our taxes submitted by the deadline. It is now crunch time to finish before time runs out and penalties are assessed. Despite the desire to just finish our taxes, we should all take a step back and think about tax estimation.

Tax liability estimation is a very useful skill to have. Put to good use, it can slash your taxes and bring your freedom date closer. It allows you to leverage your knowledge of tax liability with your employer to lower your tax withholding from your paycheck and have a higher take-home pay each month.

Because estimating your taxes allows you to lower your tax withholding and not have a tax refund at the end of the year, you are able to put your money to work sooner gaining precious days and months on your freedom date.

How Tax Estimation Found an Extra $3600 for Me

As I worked with my tax preparation provider (paid for by work), I prepared a tax estimation spreadsheet. There are numerous calculators out there for estimating taxes, but none are as powerful and customizable as the simple spreadsheet. I developed it using the infamous Form 1040. Taxes always have a mystique of being complicated and impossible to do without help, but through my creation of this tool, I learned that it is not nearly as complicated as we are led to believe.

I went through the 1040 line-by-line and brought all applicable items over to the spreadsheet to be able to calculate my actual tax liability. Because I have the expat package now, this was a huge tool for me. I have $15,000+ per year that is un-taxed from my perspective because of gross-up taxes paid by the company. My tax preparers are doing my taxes based on not saving any money to tax-advantaged accounts and after I was able to estimate my tax liability for the next year, I was able to get them to lower my taxes over $300 per month. That is $3,600 for the year that I can invest up to a year earlier and get compound growth on.

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The 1040

The 1040 is broken up into sections to make it easier to understand. The sections are:

  • Filing Status (single, married filing joint, married filing separate, head of household, qualifying widow)
  • Exemptions (Used for the standard exemption calculation)
  • Income (All your various income streams are accounted here)
  • Adjusted Gross Income (allowed deductions to your taxable income)
  • Tax and Credits
  • Other Taxes (additional special taxes e.g. self-employment tax)
  • Payments (how much you paid for the year)
  • Refund (if overpaid on taxes throughout the year)
  • Amount You Owe (if underpaid on tax throughout the year)

There is a total of 79 line items to fill out on the 1040, but for most people, the majority of the items will be not applicable and the form quickly becomes very easy to fill out.

There are numerous software tools to help you fill out your taxes, but the tax forms are not complicated and can be filled out personally. Doing this will give you a more intimate knowledge of taxes and help you to slash through the waste.

How to Estimate Your Taxes

Everybody should track their income and expenses. Because you track your income and expenses, it is very easy to estimate your tax liability for the year.


First, you need to be able to project your income. This includes not only your salary, but dividends in your taxable investment accounts, business income, taxable refunds, capital gains from investment sales, taxable retirement income, rental income, farm income, unemployment compensation, and other miscellaneous income. Basically, if you make money in any way, Uncle Sam wants a part of it.

From this list of taxable income, you should take notice of the dividends, capital gains, and retirement income. These are your personal options to reduce taxes from your income. These may not seem like income during the year, but Uncle Sam sees it that way.

Adjusted Gross Income (AGI)

Second, you will estimate your deductions for the year. Your AGI is your income after allowed adjustments to income before the personal and standard deductions. AGI gives you an overview of your income that wasn’t saved into tax-advantaged accounts or spent on tax-advantaged goods. Your main adjustments are:

  • Educator expenses
  • Health Savings Account (HSA) contributions
  • One-half of Self-Employment Tax
  • Pre-tax retirement plan contributions (Traditional IRA, SEP, SIMPLE, Solo 401k, 401k)
  • Self-employed health insurance deduction
  • Student loan interest deduction
  • Tuition and fees to qualifying schools

This list is not comprehensive but represents the most common deductions taken on your taxes. Normally the 401k deduction is accounted for on your W-2 and does not show up as income, however, when estimating your taxes, you should include it as a line item under AGI.

Tax and Credits

Tax and Credits are home to your personal and standard or itemized deductions. After subtracting these from your AGI, you get your taxable income. From your taxable income, you can determine which tax bracket you fit in and determine your taxes.

The US uses a progressive income tax. In other words, being in the 25% tax bracket does not mean you pay 25% of your income to Uncle Sam, it means you pay 25% of the amount above the 15% tax bracket and 15% of the amount between 10 and 15% brackets, and 10% of the amount below the 10% bracket.

tax ~= taxable income * 25%
tax = 10% * 10% tax bracket + 15% * (15% – 10% tax brackets) + 25% * (25% – 15% tax brackets) + …

You pay less than your tax bracket sounds like.

You have your tax liability calculated and now it is time to take your tax credits. Credits are much more powerful than deductions because they directly effect the tax liability. They are directly subtracted from the tax liability. Credits available include:

  • Foreign tax credit
  • Dependent care credit
  • Education Credit
  • Retirement savings contributions credit
  • Child tax credit
  • Residential energy credits
  • Other credits

Bringing it all together

Now we have enough information to estimate our tax liability. When we know our salary, contributions to tax-advantaged accounts, deductions, and credits, we can accurately estimate our tax liability for the year. Even if you get a bonus or some other windfall, your estimation is accurate and the bonus is just added in on top of what you already predicted.

The true power of the estimation is the chance for optimization. With a plan for the year and a model you can manipulate, you can see how different scenarios can effect your bottom line. The goal here is to minimize your tax liability and the only way to do that is to know how it works. By playing with the numbers you can watch the tax liability vary and determine the best way to plan out your taxes.

Spending your time on optimizing your taxes and determining how to qualify for the various tax credits will give you a huge return on investment. Not only can you minimize your tax liability today and get your money invested sooner (no tax refund), but you can also have more money overall by minimizing and planning your tax approach.

Check out my FREE tax estimator and save $1000s.

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  1. Another great article when I was searching Google! Thanks and looking forward to reading more of your blog in the future.

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