The Tax Agency has not made the income tax return manual accessible for decades. A Valencian man did it in three hours

“Javier, has the program PADRE come out yet?” Every year, at the end of March, my father—not to be confused with my FATHER—asked me the same question, because I was like an AI alerting him that he could finally get down to it. the income tax return every year. For him that was not just an obligation. I would say it was a hobby. Almost a passion. Something to which he dedicated hours and hours in his office armed with his pens, his tight handwriting, his calculator and of course with the Nobel package next to it.

He is no longer here, but if I have not inherited something from him, it is that passion for filing income tax returns. In fact, I have never done it, perhaps because as I saw that he dedicated so many hours and effort to making it perfect, that caused me some trauma. “Ugh, this costs too much,” I told myself then and I continue to tell myself now. And here I am, with a reverential fear of completing that task, which I end up entrusting to a manager because time, they say, is money.

And yet, it is a small outstanding debt that I have. Last year I tried to try it, and this year I told myself that maybe with the help of some local AI model (because of privacy) I should try it again. But while I was thinking about it, these days the practical manual of Income 2025and one person decided to do something very interesting with that information: he turned it into something useful.

This is how the LaRenta.es Open Source project emerged

This manual, no matter how complete and detailed it may be, has a problem: it is very inaccessible. The information is there, but neither the wording nor the structure or its organization make it a particularly useful document for most users.

That’s where it came into action. Paul March (@paumrch), a public administration worker who lives in Valencia and who, at 31 years old, has a profile completely aligned with the so-called civic technology. Although his training is not technical, he is a very restless self-taught person who has been “tinkering” with all kinds of personal technological projects for more than 15 years. And the latter has become especially popular.

We have had the opportunity to speak with Pau and he told us that by working in public administration and being interested in the application of technology to his field, “I have always been interested in the issue of digitalization of the administration because I know it and I know the room for improvement there is and I am convinced that citizens need that improvement.”

When the Income 2025 practical manual appeared, he realized that he could try to do something with it. With the experience of previous projects and the new AI tools that he had been using for months, he got the ball rolling. In just three hours, he confesses, he created LaRenta.esa web service that allows any user Know what state and regional deductions you can take advantage of in this statement.

To do this, it has created a very simple system in which, from a small questionnaire that takes two minutes to complete, we can obtain information about these deductions. The process is reduced to going through seven stages of this questionnaire with a few questions, from which it is possible to obtain a final summary with deductions to which we may end up being entitled.

And in each of them, we will have an indicator to know what percentage of the total of each deduction we may be entitled to, as well as detailed information about each particular deduction. In these details, the information present in the 2025 income manual is used more clearly and directly, but although the language is still somewhat harsh, at least in this project only that which is directly related to that deduction is shown in a more readable format.

We are therefore faced with a project that is not intended at all to prepare your income tax return, but rather to at least provide the information that exists is more accessible and easier to understand. And as March says, it is far from being a perfect project, but it certainly shows that all that information offered by the public administration can be converted into something even more useful in a relatively simple way.

From idea to application in three hours

These days this entrepreneur explained the process of creating this webapp in an article posted on his Twitter account (X), and as I said there, the cycle was surprisingly simple.

AI was his companion throughout the project, and he took advantage of his experience with previous projects to then take advantage of several tools:

• The interface design was carried out with the help of GoogleStitch
• The programming was done with the plugin Claude Code in Visual Studio Code.
• He used Opus 4.6 to plan the entire project, and Sonnet 4.6 to program it, although for some basic tasks he indicates that he also used Anthropic’s basic model, Haiku.

He did it all on March 19, right during the Cremá, the big day of the Fallas in his city, Valencia. The project absorbed him so much that he didn’t even enjoy the party and he spent that afternoon and part of the night polishing the errors he was detecting.

The result, as can be seen on LaRenta.es, is a fully functional, fast, clear and practical web application. Not only that: it is totally private. Pau explains that no data is saved except for the email if a user wants the summary PDF report to be sent to them.

The potential of civic technology

When the project was finished, Pau decided post a message to share it through your Twitter account. He mentioned some of his references on this social network as José Luis Antúnez either Jaime Gómez-Obregón —whom he loves to read on this network, he confesses—, and they in turn shared the project, which ended up helping its popularity soar.

Shortly after publishing it, some users suggested that he turn it into an Open Source project, and Pau did just that: shared the code on GitHub and from there he began to receive some suggestions for improvement (pull requests) and also notifications of things that were failing (issues). The LaRenta.es website has not stopped receiving visits since then: “there are already 55,000 people who have entered, and several thousand have completed the wizard.”

For Pau March, the success of LaRenta.es shows that there is a real demand for clearer public services. Its vision is simple: current technology allows the information that the State already has to reach the citizen in a more direct and simple way. “It is about exposing a reality: that the administration can make information more accessible. The technical means are there,” he explains.

This project shows that this change is feasible. “That LaRenta.es works means that it is necessary, and if it is, it is because there is a huge gap from the administration towards the citizen and also towards the company.” For him, his project is just a way of make the State see that things can be done better. And just to fill out the income tax return, for example, Pau asks himself “Why TaxDown “Can’t the Tax Agency do it?”

It is an interesting and important question, especially now that we actually have tools that would make this type of project easier than ever. Now it remains to be seen where LaRenta.es goes, but Pau March already plans to resume developments that he had started in the past and that go in that same direction.

In the meantime, yes, I am afraid that I will still not dare to file my income tax return myself. And every March I will continue to remember how my father, armed with his pack of Nobel in his shirt pocket, asked me day after day if the rental program was already available.

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