Application developer guest post - online tax calculator

Welcome to the fourth in our series of guest blog posts written by community members who have developed applications using data available on This week, David deSouza writes about the online tax calculator application.


When I heard that the government had decided to release over 4000 public data sets,  which could be searched from one location, it got me a little excited. I have always thought that data should be free, allowing people to spot trends, make decisions, and hold the government accountable. Now that my wish had come true the question was - what was I going to do with all this data?


Having data is one thing but turning that data into meaningful and actionable information is quite another. When I learnt that was encouraging people to create an app I thought it was an excellent opportunity to scratch my data itch and make something interesting, creative and useful.

Having a background in finance I was drawn towards the resources that HM Revenue & Customs had available. This included a treasure trove of data such as tax receipts, incomes and charitable donations. After playing around with the data and noticing some interesting trends I remembered the Pareto Principal which states that 80% of effects come from 20% of causes. I thought it would be interesting to see if this rule would hold true for the jobs that contribute most to the government’s cash flow, i.e., does 80% of the government’s tax revenue come from 20% of the available jobs?


Planning the creation of the app was probably the most time consuming part of the whole process. The vast amount of available data became over whelming, even though I was only using a small subsection of data from just one governmental department.

The resource section of the website was very useful to help analyse, adapt and sort through all the data that was available. This section of the website also contains a number of videos and tutorials on how to use the data. Without these tools I would certainly have spent many more hours scratching my head during the planning phase.

Technical Approach

I wanted the app to have two objectives. Not only did I want it display which jobs paid the most tax but I also wanted the app to be interactive. To meet this objective the app would allow people to select their job sector and the year they started working. The calculator would then work out how much tax they had paid and how this compared to the average job.

In order to reconcile the graphical and technical sides of the application I had to recruit the help of a graphical designer and programmer. I used Microsoft Excel to manipulate the data and create the graphs I wanted. Excel also helped me convey the calculations the app needed to perform to the programmer.

In conclusion, the planning, designing and building of our app was very successful. The whole process not only helped us visualise the data presented but also allowed our website to gain some exposure from people who were interested in what we had done. I hope to take what we have learned and create additional applications using the vast resources available at I strongly encourage others to make use of all this data which, until recently, was locked away deep in the bureaucracy of government.

David deSouza loves data visualisation and is the owner of TaxFix – An online tax rebate and tax return company.

1 comment

  1. Anonymous

    online tax calculator? I don't know about it, please tell me?

    Link to this comment