Senior Research Engineer in Automated Reasoning (m/f/d)

Berlin - Engineering

Our story:

Every year millions of people are either filing their taxes in fear or giving up on their tax refund altogether. We're working on fixing that. Our intuitive app enables anyone, regardless of education or background, to file their taxes with newfound confidence.

Spread across Berlin and Madrid, Team Taxfix is a compassionate group of solution-finders. We speak our minds openly, and with 250+ professionals from 40 different nationalities, we're rich in ideas and voices. In four years, we've raised over 100 million euros in funding and helped people reclaim more than 400 million euros. 

Your challenge: 

As a Senior Research Engineer, you will be part of a talented multidisciplinary product team. Working with the latest technologies, you will take ownership of the development and optimisation of reasoning algorithms for our tax expert system. Through in-depth research, you'll lead the implementation of new algorithms and optimisations. This is a hands-on role where we will fully support your education in a new programming language—Elixir, with team training and mentoring. You'll also have access to a generous learning and development budget so that you can learn in the style that suits you best.


Your responsibilities:

  • Define the best algorithms and data structures to use in our knowledge base implementation.
  • Define how to evaluate system correctness.
  • Prioritize algorithmic optimization initiatives that improve performance.
  • Develop an understanding of our forward-chaining algorithms implemented in our in-house knowledge base.  
  • Identify inefficiency in our algorithms and propose new approaches to improve performance, leading implementations of new algorithms and optimizations.   
  • Develop methodologies for the evaluation of correctness of algorithms, and contribute to the design on performance tests. 
  • Learn the Elixir programming language and the stack used for the implementation of our Tax expert system.


Your profile: 

  • M.Sc / PhD in computer science or related field like Mathematics or Physics. 
  • 5+ years industry or academic experience in the Automated Reasoning domain.
  • In Depth Knowledge of SAT, Forward Chaining, Backward chaining, RETE as well as Algorithm Development and Optimization.
  • Understanding of Knowledge Representation and Expert Systems. 
  • A hands on approach with coding teamed with a curiosity to learn new technologies like Elixir. 
  • Excitement for collaboration with different specialists in our Product, Engineering and Business teams.


Why Taxfix?

  • A chance to do meaningful, people-centric work with an international team of passionate professionals. 
  • Holistic wellbeing with mental health coaching sessions, a discounted membership to Urban Sports Club, and supplemental child care support. 
  • Employee stock options for all employees—because everyone deserves to benefit from the success they help to create. 
  • A generous learning budget to support your personal and professional development and guidance from our internal L&D experts.
  • Full trust to take ownership of your work in a flat hierarchy where feedback is encouraged and expected. 
  • Dedicated relocation and visa support for those that need it. 
  • Choose to work from home or our modern office when needed—plus healthy drinks and snacks when you do come in.
  • Plenty of opportunities to socialise as a team. In addition to internal tech meetups, our international team hosts regular get-togethers—virtually and in person when possible.

Excited? So are we. Learn more about
Team Taxfix on our blog and get a glimpse of our culture below:


At Taxfix, we don't just accept diversity—we celebrate it. We're proudly committed to equal employment opportunities no matter your gender, race, religion, age, sexual orientation, colour, disability, or place of origin. We cherish each person's individual contribution to our overall identity, purpose, and goals. Join us!