Before I tell you the story, there is one very important detail you must know: Not all Casio calculators can store a tax rate.

Step 3: When the display changes (e.g., shows "TAX %" or a blinking number), type your tax rate using the number keys. Example: type 8 . 5 for 8.5%.

Setting the tax rate on your Casio calculator is essential for individuals and businesses that need to calculate taxes regularly. By programming the tax rate into your calculator, you can quickly and accurately calculate taxes on various financial transactions, such as sales, purchases, and income. This feature is particularly useful for:

  • Casio MS-80B
  • Casio MS-100B
  • Casio MS-120B
  • Casio HR-100TM
  • Casio HR-200TM
  • Some Casio models label the tax function as [GT/TAX], [TAX+]/[TAX-], or use a dedicated [%TAX] key—look just above the keys for the TAX+ and TAX- labels.
  • If you need to change the rate, simply repeat steps 2–3 with the new percentage.

Standard Method (for most MS and DJ series):

Step 1: Turn on the calculator and press the AC (All Clear) button to reset any pending operations.

For models where RATE SET is explicitly labeled (like the MS-20UC or WM-320MT): Clear Entry: Press [AC].

Once programmed, the calculator retains this rate even if turned off, as long as it has power. CASIO【How to use calculator Tax calculations】

Setting the tax rate on your Casio calculator is a one-time task that saves you from doing manual math every time you need to calculate a grand total or strip tax away from a price. Whether you are using a standard desk model (like the MS-80B) or a heavy-duty printing calculator, the process is nearly identical across most Casio "Tax & Exchange" series.