It is natural to worry about using a different brand toner in your printer. After all, the printer is an essential piece of modern equipment, and we value it. There are so many legal requirements and caveats on everything we own that it all dies down to a dull roar. Every single purchase you have ever made with your computer required you to sign a host of EULAs, not one of which has anyone ever read or understood. The printer says that using a third-party toner cartridge may violate the warranty. Is this true? Absolutely not. Not only is it false, but if it were true it would be in direct violation of United States law.
The Magnuson-Moss Warranty Act of 1975 protects the American customer’s right to purchase compatible supplies. That means, by law, that if a company warranties a device, and you purchase supplies that should work normally with that device, the warranty is still valid. In other words, the warranty on a blender should not be void if you buy fruit from a different store than the people who sold you the blender, and the warranty on your printer should not be disregarded only because you buy ink from a different company. A warrantied product should not break when used with compatible products.
The key word is "compatible". Refill kits are a little bit more of a grey area. Not only are they not exactly "compatible," in a lot of cases they are specifically non-compatible. The law is extremely clear about off-brand or remanufactured printer cartridges; they do not void a warranty. The law is less clear about refill kits.
There is only one way that you could have a problem. If your cartridge directly causes damage to the printer, the error is your responsibility Fortunately remanufactured and off-brand cartridges have equivalent failure rates to the official brands, so this is almost never a problem. If you use a refill kit and the cartridge damages the printer you are also liable. Refill kits often have the same negligible failure rate as remanufactured cartridges, but since the refiller may not have been properly trained or educated the chance of malfunction can greatly increase.
Though the big printing companies would obviously prefer that you keep buying their expensive name-brand printer cartridges, the law clearly protects the consumers. Thanks to the foresight of the 1975 Congress, decades before inkjet printers were ever invented, your right to save money by purchasing remanufactured and off-brand inkjet cartridges is secure. No matter what it may please them to hide in their fine print, you have the full force of the federal government on your side. Do not let them take your warranty away. The government requires that they stand behind their product, and it is up to you to hold them to it.