When doing work that frequently involves tax rates, using a calculator that automatically applies the current tax rate saves time and keystrokes. Both stand-alone and software calculators include such tax rate features, but they not standard, and only some makers include the function. Setting the tax rate allows you to deal with different tax conditions or changes to tax rates.
Finding calculators with tax rate keys isn't difficult. Calculator manufacturers such as Texas Instruments, Canon and Casio offer tax functions on both printing and non-printing calculators, at a variety of price points. Proprietary brand calculators offered by office supply retailers may also be available with tax functions. Calculators with tax functions may use two keys, TAX+ and TAX-, to add or subtract the tax rate to an amount, or instead may use a single TAX key in combination with plus and minus keys. Some models might also include a separate RATE key, instead of using key combinations to store tax settings on the calculator.
While each manufacturer implements different procedures to program tax rates, the general steps are common. On calculators without a RATE key, words such as "SET," RATE," or "RATE SET" will be printed above a key on the calculator case. Pressing and holding another key prepares the calculator to accept your tax rate. For example, to add 13 percent tax rate on a Casio calculator, press and hold the "AC" key and press the "%" key -- which has the word SET printed above it -- for two seconds, then enter "13.0" and press the "AC" key. The TAX+ and TAX- keys will now add or subtract 13 percent. Check the manufacturer's instructions for the specific steps your calculator requires.
Software calculators often mimic both the features and design of standalone calculators. Tax functions aren't standard in the software world either, but are included with some packages and programmable into others. Moffsoft Calculator 2 includes a single TAX key, while RUCalc uses the TAX+ and TAX- dual-key method. Both methods work in the same manner as stand-alone calculators. CalcTape's free version allows two custom keys that can be programmed for setting tax rates. The RUCalc software is free and, while Moffsoft does offer a free version, it does not include tax key functions.
Change tax rates on software calculators using options, user functions or preferences, depending on which software you are using. For example, on the RUCalc, set the tax rate by clicking "Options" from the menu bar, selecting "Preferences," then (based on the previous example) typing "13.0" into the Tax Value box.