So I recently moved from Berlin back to my hometown Copenhagen. I also got serious about paying into a pension plan. Which made my tax situation a big mess, estimating my 2023 taxes felt like signing a mortgage contract in colored crayon.
"How hard could it be?"
“Tax laws are really just closed systems“, a younger, idiot-version of me deducted, not feeling the future headache it had just sparked. "To build a model that accounts for 80% of the important stuff—how hard could that be?”
Well, dear reader, a month and a half later I'm here to tell you: Pretty hard.
Which is why I’m happy I’m finally done with this estimator enough that:
It actually works
It provides practical for one of the >0.5% of earth's population who needs to project their Danish income tax using only 1 data point.
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Hobby Horse-led Development
Snark aside, making tools for yourself, then releasing them publicly, is such a wonderfully myopic, hobby-horse driven quirky process I will never stop loving.
Take the name ("Please!" 🥁). Yeah it's corny, but I have this personal rule: Very Serious Projects get dumb, silly names that make them feel easier—less overwhelming—as I'm building them.
How it's built
Tax-A-Tron EZ-Estimator 4000 is built on Decipad, which is sort of like Excel, but fun. The tool has 4 sections:
Quick Result (gross → net income)
Accuracy Enhancer (deductible expenses)
Under The Hood
The calculation formulas lean on the calculation methods in a spreadsheet for estimating income tax developed and published by a citizen watch group for Danish tax legislation Tax.dk.
A crucial difference between that spreadsheet and The Tax-A-Tron EZ-Estimator4000 is about focus. The goal with the Tax-A-Tron is usable by 80% to get 90% of the way there.