<prompt> Human: Im going to spend about 3000 on a diamond ring because thats what I have set aside over time specifically to do. I have that money.What has occurred to me after doing a ton of research is that, if I buy online at a place like enchanteddiamonds.com or jamesallen.com, I wont have to pay sales tax since Im in California.If I buy at a store in Cali, then Ill have to pay about 300 in taxes.Will I have to pay taxes for the online stores later on when I file though?  <response>: Legally, you are supposed to keep track of all transactions where you owe sales tax but the vendor fails to collect it, and you are supposed to pay the sales tax you owe to the state. In theory you could be billed for sales tax you owe - if the state finds out. It does seem unlikely but could happen. Fun story: I know of someone who lived in New York city and was buying cartoons of cigarettes online from a vendor who lives on an Indian reservation, which allowed the person to evade paying the crazy taxes NYC imposes. The city somehow caught on that this was happening, did an audit, and billed my friend for the taxes he had avoided. So yeah, low probability but not impossible. 