Tuesday, April 20, 2010

Shared Apartment Expenses Spreadsheet

Have you ever been in that situation where you are sharing a living space with a number of other people and you are constantly trying to figure out who owes who what because each utility is in a different person's name? I've moved fourteen times in the past six years (because of going back-and-forth from university to co-op every semester) and I've had different roommates at each location. I needed a quick and easy way to keep track of who owed me money or what I owed someone else and to make sure all the bills were paid. I wanted this to stay updated in real time so I could simply look at it whenever and know exactly what was due and who to pay, all without needing to sit down do the math every time. This has lead to the creation of my Shared Apartment Expenses Spreadsheet. The following example is for an apartment with three roommates.

The first thing I do is list a description of what utility or rent is due. In the next column I list the amount due. The next column is the category where the expense falls under. These are actually drop-down lists which originate on another sheet where I listed out all of the possible categories. See data validation if you don't know how to make a drop down list. I only did this so I could look at statistics for each month and category.

I also put the due date for each bill and when it was actually paid for my records. Now the important part: who paid what? I make a column for each person and every time they pay a bill I put the amount under their name next to the item that they paid. 

The next section is who owes who what. Now this could be a simple formula if you have decided to split everything evenly among yourselves. But come on, life is never that simple. The apartment I am living in has a one car garage and a master bedroom. It's not really fair to the person that gets screwed out of the garage and doesn't even get their own bedroom! Therefore, we decided to split the rent like so: 
  Instead of having a simple formula you have to manually enter the amounts for the rent. Every other utility is split evenly. The totals are listed at the bottom of the columns. Now, the next thing we want to prevent is to have to write a million checks. If you owe me money, but I owe you more money, I simply subtract what you owe me then write you a check. 

Next is the all important who paid what. This is more complicated and confusing the more people you have but it works and in the end makes things much easier. I list each person and what they've paid to the other two people. I then add up the total at the bottom.

Alright, so that's the easy and obvious part but I want to know what the balance is right now. Below the who paid what section is where the magic happens. First, in cell R16 I take what Nick owes Brian and subtract what Nick PAID Brian (=K12-R12). In the next cell I take what Nick owes Ron and subtract what Nick PAID Ron (=L12-S12) and so on for the other two people. Now we can see who owes who what after payments. Brian owed Nick $86.71 but after a payment of $22.16 only owes him $64.55.

However, Nick also owes Brian $31.67, which is less than what Brian owes Nick. So, we subtract what Brian owes Nick so that Brian just has to pay Nick $32.88 instead of $64.55. Make sense? The formula looks like this: 


If what Nick owes Brian is greater than what Brian owes Nick, subtract the two, otherwise put zero. Nick's balance for Brian is zero. Brian's balance is greater than Nick's so subtract the two and get $32.88. Basically, each person either has a zero balance or they owe money to someone. There should be no negative values.

The last line tells you who you owe money to in real time. Every time someone makes a bill payment or pays someone else it automatically updates and adjusts the values. No math involved! No more fighting over who paid what and when.

On the last sheet (Statistics) I decided to get a little crazy and keep track of some statistics: the totals for each month and which utility was the biggest drain on my wallet. I used this formula for the utilities


And this formula for the months: 


This is also a good place to check the totals with the master sheet to ensure your work is correct.

I had to make some quick graphs to visualize the data. Who doesn't love a good pie chart? 

And there you have it, another practical, real world application of Microsoft Excel!