The Gentle January series shares one practical privacy tip a day from a Markup staffer who actually uses the advice in their own life.

Through the first three weeks of Gentle January, the privacy tips Markup staff passed along to readers have been almost entirely digital in nature—ways to acquire and configure hardware, software, and services, and ways to behave (or not) on the internet.

If there’s one thing we’ve learned from the email sent in by readers so far this month it’s not to forget about the real world—the physical artifacts all around us and the old-fashioned networks that long predate the internet.

For example, here is some advice from a reader named Tai on how to protect your personal data while also exercising a bit of fiscal responsibility:

I have a tip for increasing personal privacy: use cash when possible.

For example, if you’re going to buy pizza or any other purchase you know you won’t return, then cash will give you much financial privacy. Even if returns are necessary, then choose stores and places where the process, with a receipt, can be done with ease and very little friction.

Credit card companies are known to use information from purchase transactions to customize ads to credit card customers down the data mining business line.

One can consult various other financial education sites for much more detailed approaches, though a coincidental upside of cash is that one can’t overspend if you walk into an in-person store with cash. Sounds very obvious, though the restriction of only being able to spend what you have at hand can be helpful with preventing overspending.

I hope this may be of use to readers if chosen.

It is true that a robust market seems to have formed around mining data about credit card transactions; as Washington Post columnist Geoffrey Fowler wrote in 2019, “the card data business is booming.” The following year, Fast Company reported that cardholders are “now shopping in a panopticon, with companies tracking and analyzing their purchases in near real time.” This brisk trade, coupled with a lack of strong federal protections for consumer privacy, led the American Civil Liberties Union to reach much the same conclusion as Tai: “Simply put, cash is good for keeping people from prying into our lives, and credit cards are not.”

Other readers wrote in to highlight the importance of protecting sensitive documents and packaging before setting it out in your trash. Here is advice from Chelsey:

One privacy tip that I do is shred, or peel off and cut up, my personal information on packages and letters delivered to my home. When you order something online, the delivery address often includes your phone number and email address. I also shred the personal information of my friends’ return addresses when they send me something.

Reader Josh had similar advice:

It definitely has caused some people to accuse me of having a tin foil hat, but I follow the rule of not putting my identity or the identities of anyone else in my house in the bin. 

This means that addresses on packages, letters, etc. are struck through or shredded before being recycled or put in waste. 

I make sure that noone could ever get my name and address from something they’ve found in the refuse. 

You don’t need to be paranoid to engage in such precautions. The U.S. Federal Trade Commission recommends shredding documents with personal information to protect against identity theft, while the Department of Justice cites discarded credit card offers as a common vector for identity theft. A 2019 report from the University of Texas at Austin’s Center for Identity estimates that 24 percent of personal information theft is “non-digital,” although this includes theft of not just documents but also physical things containing digital data, like laptops.

Thank you to Tai, Chelsey, Josh, and all the other readers who have sent in their tips thus far. We will feature reader advice in at least one more post before the end of Gentle January. See the box below to submit your own.