what is a zero day

What is a Zero Day?

What is a zero day? Where does the name come from? Why did you choose it? People have asked me all of these questions and more, so I decided I should set the record straight.

The name “zero day” is a reference to my previous job. I used to work in Cyber Security for a large defense contractor. From time to time, we would come across zero days:

“an undisclosed computer-software vulnerability that hackers can exploit to adversely affect computer programs, data, additional computers or a network.”

Basically, a “zero day” with respect to software is a piece of code that lets an attacker control your system. It is an exploit, a cheat. These were the zero days that I lived with.

When I started Zero Day Finance, I needed to come up with a name. I wanted it to reference my past as a small hint. I also wanted the name to relate to the financial strategy that I was developing to help reduce my spending.

“Zero day” fit in very nicely, because it not only references my past work, but also relates directly to spending — rather not spending. So I decided to run with that name: Zero Day  Finance. But what exactly is a zero day? What constitutes a zero day?

Understanding this is important because you will be tracking them every day as part of the Zero Day Challenge.

At first, a “zero day” was any day where I spent exactly $0. This definition served a very useful purpose, until I got a few refunds on my credit card. On those days, my spending wasn’t $0, but rather it was less than $0.

This lead to the creation of a new definition: a “zero day” is any day where my net spending is less than or equal to $0. This definition is more efficient because it lets me take credit card refunds into account.


In the Zero Day Challenge spreadsheet, I use this definition of a zero day. Join the mailing list to get your copy today!


But this definition also creates some complexity. Let’s say that I get a $50 refund on my credit card, but I also spend $10 for lunch on that day. My net spending is -$40, so that’s a zero day, right?

Well, it depends.

The way I do my financial tracking, that is 100% a zero day. My rationale is that I stick to simple definitions of “zero day” and don’t want to create a bunch of *if* clauses with exceptions. In addition, I’ve already lost a zero day to the spending, so why not gain a zero day from the refund?

But the Zero Day Challenge purists don’t like this. Any day with spending is a zero day, they say!

So who is right? Doesn’t really matter. The Zero Day Challenge isn’t about subscribing to a large set of rules where we compare ourselves on a leader board, competing for the first prize.

The Zero Day Challenge is about finding inner happiness from things other than spending money. About figuring out how to reduce expenses, save more money, and retire early. So it doesn’t really matter what your definition of a “zero day” is, as long as you are consistent, and work towards your goal.

Are you ready to take the Zero Day Challenge? Find out now!

Comments 4

  1. Thanks for breaking down the logic! Not going to lie, if I put $20 on my Starbucks card and that last 4 days, then I didn’t spend on those days and they ARE zero days to me. But that’s just me and not everyone may do it that way!

    1. Post
      Author

      I would agree that those days are zero days. That’s because you bought $20 worth of coffee on the first day. Not everyone will agree, but as long as you’re consistent, everything will work out.

  2. It’s funny how people get so caught up in the ‘rules’ they forget the purpose of the task. For me I don’t get many refunds so if I spend money or a voucher to get a product/service that breaks my zero day. The idea for me is to me more conscious about whether I really need that item, whether it is paid for by me or someone else (gift card) is irrelevant.

    1. Post
      Author

      That’s the goal! Even if you aren’t super successful in the Zero Day Challenge (money wise at least), you’ll have spent a lot of time thinking about the true value of what you buy, and if it’s really worth it.

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