How to Calculate the Corporate Tax Rate?

For a calendar year corporate tax return, the tax rate is fairly simple.  For 2017, you use the old rules (15% on the first $50,000, 25% on the next $25,000, etc.) and for 2018, it is simply a flat 21%.

However, for corporations with a fiscal year-end, it is slightly more complicated.  The formula is to take the number of days in 2017 and apply that rate to that share of income and then take the number of days in 2018 and apply that rate.  You do not calculate separate income for 2017 and 2018.

Let’s look at an example:

LMN Farm Corporation has a March 31, 2018 year-end.  It earned exactly $50,000 of income.   The number of days before January 1, 2018 is 275 or 75.34%.  The tax on $50,000 is $7,500 times 75.34% equals $5,650.50.  The tax on $50,000 in 2018 is 21% or $10,500 times 24.66% or $2,589.79.  If we add these two numbers together we get $8,240 (rounded).  That is the amount of tax this corporation will pay for the year ended March 31, 2018.

Most tax software should calculate this number automatically.  If you are preparing a corporate return manually, this will be the formula you use.

  • Principal
  • CliftonLarsonAllen
  • Yakima, Washington
  • 509-823-2920

Paul Neiffer is a certified public accountant and business advisor specializing in income taxation, accounting services, and succession planning for farmers and agribusiness processors. Paul is a principal with CliftonLarsonAllen in Yakima, Washington, as well as a regular speaker at national conferences and contributor at Raised on a farm in central Washington, he has been immersed in the ag industry his entire life, including the last 30 years professionally. In fact, Paul drives a combine each summer for his cousins and that is what he considers a vacation.


Paul, I finally got the reassurance I needed. While there was an intent to make reference to Sec. 15, the lack of a specific reference to Sec 15 is not viewed to mean that it doesn’t apply. That’s the JCT position. Thus, I am comfortable that a blended rate applies. I guess we follow the general fallacy – that the Congress is presumed to know what they are doing when they draft statutory language.

Do the new 2018-199A opportunities have the same benefit to farmers that are incorporated?

No. This only for non-corporate farmers. Corporations got their benefit by reducing the top rate form 35% to 21%. Although most farmers only paid 15% so their rate went up 40%.

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