References / Payminator ❘ Daně
Payminator ❘ Daně
An online wizard for personal income tax returns that Payminator offers together with the advisory firm RSM. We designed the whole application and develop all of it – from the tax calculation to the official outputs and a draft submission in the client's government data box.
70+
wizard screens
§6–10
all types of income
270+
automated tests
RSM
tax adviser review
About the project
A tax adviser in your browser
It asks questions like an adviser, not like a form.
Payminator Daně guides an individual through the entire tax return – from employment through self-employment, rentals and capital income to income from abroad. The wizard skips whatever does not apply, and whatever the user fills in is checked immediately and reflected in the tax calculated as they go.
Under the surface there are two separate applications. The Symfony backend holds the calculation, the rules and the connections to the authorities, and exposes them through GraphQL. The Next.js and React web interface uses it to build the wizard in Czech and English.
Before filing, the finished return can be reviewed by a tax adviser from RSM. They go through it section by section and send errors back to the client with a comment, and the application makes sure they get fixed.
Under the hood
From the wizard to the data box
The answers in the wizard feed a single calculation. From it, the application builds the XML for EPO, fills in the official form with its annexes, prepares a QR payment and creates a draft message to the right tax office in the client's data box. The client just checks it and sends it.
What we solved
Five areas the application is built on
From the first question to the adviser's review and secure sign-in.
A wizard instead of a form
Questions come in the order people know them in, and every field gets feedback straight from the server.
Tax and advance calculation
All types of income, including foreign income with the credit and exemption methods, tax credits, child benefits and future tax advances.
Review by an RSM adviser
The adviser goes through the return section by section and marks errors, and the application tracks their correction. The adviser and the client message each other right in the application.
Pre-filled from the payroll app
Employees of companies that run payroll in Payminator load their income details with a single consent.
Sign-in and security
A custom OAuth2 server, sign-in with Google, Apple, Seznam or Microsoft, and two-factor authentication by e-mail.
Operation
Ready for the season
Most users come just before the filing deadline. That is why the web interface runs in multiple instances, and monitoring reports errors before anyone notices them.
Development
A new form every year
Rates, credits and limits are season parameters in the database, not in the code. The calculation and the form each have their own version per tax year, so the next year does not overwrite the previous one.
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