Your Tax Data Online: 6 Questions for Any Provider (2026)

Updated on 25.07.2026

When you upload your salary certificate, bank statements and pillar 3a statement somewhere, the decisive question is not whether the provider is "secure". Everyone writes that on their website. What matters are six concrete questions: In which country are your documents processed and stored? Is an AI model trained on them? How quickly is your data really gone after deletion, backups included? Who is legally responsible, and under which law? Which other companies are involved? And what can you demand if you want to know exactly? Every one of these has a checkable answer that should sit on a public page of the provider. This article shows you how to find those answers, and answers all six for TaxWize openly, including the places where other routes come out ahead.

The copy-shop comparison

Uploading documents is a bit like handing a folder over at a copy shop. Whether copies get made is not the interesting question, that is why you went in. What matters is: does the folder stay in the shop or travel to another country? Is someone in the back room allowed to read along? Does a copy end up in an archive you have never seen? And when exactly is everything shredded?

With tax documents the stakes are higher than with a folder. Salary, wealth, debts, family situation, health insurance: that is a household's complete financial biography in a single stack. All the more reason to spend six minutes on the six questions before uploading.

Question 1: In which country are my documents processed and stored?

Look for a concrete answer: country, hosting partner, and whether any processing step leaves that country. Phrases like "your data is safe with us" or "encrypted transmission" do not answer the question, because they say nothing about where the data then sits.

A common misunderstanding: a provider can be a Swiss company and still have processing done abroad. Company seat and processing location are two different things, and only the second determines whose authorities could in theory demand access.

At TaxWize: All tax documents and the data extracted from them sit on Swiss infrastructure, hosted by Infomaniak in Swiss data centres. One step involving your payment data leaves Switzerland and is disclosed as an exception: payment processing via Stripe, which may process data in the EU and the United States. Stripe never receives your tax documents or the tax data extracted from them. Details on the data-protection page.

Question 2: Who reads along, and is an AI model trained on it?

More and more tax tools use AI to read documents. So the honest question is not "does the provider use AI" but: whose model is it, where does it run, and what happens to what it reads? With internationally operated AI assistants the answer depends heavily on the plan you are on; we have collected the sourced detail on our comparison page TaxWize and ChatGPT.

At TaxWize: The language model that reads your documents is hosted by Infomaniak in Switzerland. The text recognition for scanned pages runs self-hosted on the same Swiss infrastructure, so no further service provider reads your documents. Your content is not used to train AI models. And to be clear: AI output can be incomplete or wrong. That is why TaxWize shows you every extracted value for checking before it is used. The tax calculation itself is then a deterministic rule set built on your canton's published tariffs, not a language model; reading the documents is the AI step, and you check it.

Question 3: How quickly is my data really gone after deletion?

This is where marketing separates from substance. "You can delete your data at any time" is only half an answer, because every seriously operated platform runs nightly backups. A good answer therefore states two windows separately: when data disappears from the live systems, and when it is gone from the backups.

At TaxWize: Deleting your data in the settings removes declarations, tax calculations, extracted values, uploaded documents and recorded assets from the live systems immediately. Backups still holding that data are cleared within 30 days. There are two levels: data deletion keeps your login so you can start fresh; account deletion additionally removes the login identity and cannot be undone. Set out on the security page.

Question 4: Who is legally responsible, and which law applies?

A serious provider names the full company name, the legal form, the seat and the Swiss UID, so you can look it up in the commercial register. Without that, in a dispute you do not know who you are actually dealing with.

At TaxWize: The service is operated by Szakács Solutions, a sole proprietorship in Eggenwil, canton of Aargau, Swiss UID CHE-289.567.114, entered in the commercial register of the canton of Aargau. Swiss data protection law (DSG) applies.

Question 5: Which other companies are involved?

No provider does everything itself. The question is how many processors there are, where they sit and what they handle. A short, complete list with locations is a better sign than no list at all. Pay particular attention to payment processing: it is often the step where looking closely pays off.

At TaxWize: Four entries in the register: three external processors under a data-processing agreement, plus one component we run ourselves. Infomaniak (Switzerland) for hosting, AI-assisted document processing and email. Stripe (EU and United States) for payments, with no access to your tax documents. Plausible Analytics (EU, Germany) for cookie-free statistics: Plausible sets no cookies and collects no personal data, which is why taxwize.ch has no cookie banner. The fourth entry, Supabase (Switzerland) for the database, sign-in and file storage, is open-source software we run ourselves on the same Swiss infrastructure, not a service we buy in.

Question 6: What can I demand if I want to know exactly?

You are not dependent on what a provider publishes voluntarily. Under Art. 25 of the Swiss Data Protection Act, whose revised version has been in force since 01.09.2023, you can request information at any time about whether and which personal data is being processed about you. The information is in principle free of charge and is normally provided within 30 days (source: FDPIC, right of access, retrieved 25.07.2026). Rights to rectification and to deletion come on top.

In practice that means an informal email to the provider's data-protection address is enough. How fast and how completely they answer is itself an answer. At TaxWize the address is privacy@taxwize.ch.

The six questions at a glance

What actually happens to an uploaded salary certificate at TaxWize

A worked example says more than any assurance. You upload your salary certificate for tax year 2025:

1. The file travels encrypted over TLS to a server in Switzerland and is placed in Swiss document storage with access controls.
2. If the page is a scan or a photo, self-hosted text recognition turns the image into text, on the same Swiss infrastructure.
3. The Swiss-hosted language model reads the text and proposes the values, for example the gross salary or the AHV deduction.
4. You see every proposed value and confirm or correct it. Only then does it count.
5. The tax calculation applies your canton's stored rules to those verified values and produces the same figure every time for the same inputs.
6. If you later delete everything, the document and the extracted values disappear from the live systems immediately, the backups within 30 days.

The prices and deadlines in this article are as of 25.07.2026. Details like these change, so check the linked pages if in doubt, or simply ask.

Where other routes come out ahead

Honesty belongs in this topic, otherwise the whole article is just advertising.

The official cantonal portal is the most data-frugal option. Your tax office already holds your tax data, so no additional party enters the picture. If data minimisation matters to you above all and you are willing to sort and type every figure yourself, your canton's portal is the right route. Any preparation layer in front of it, TaxWize included, is a deliberate trade-off: more convenience against one more party you entrust with data.

Paper and local software have their place. If you would rather upload nothing at all, you can still work locally. The trend runs towards web solutions, but as long as your canton offers a local option it is a legitimate choice.

And not everything is perfect on our side. Payment processing leaves Switzerland. On top of that there is the optional "Sign in with Google" button, which processes no tax data but is still a service from an international provider. Payment processing is stated openly on the data-protection page, the Google button on the security page, in both cases in plain text rather than buried in fine print. TaxWize has applied for the Swiss Hosting and Swiss Made Software labels, the review is running, and until a certification is actually granted we display no badge for it.

What this means for your choice

The six questions work with any provider, ours included. If you find the answers on a public page, concrete and with names rather than adjectives, that is a good sign. If you only get them by asking, that is still fine. If you do not get them at all, you know enough.

TaxWize prepares your tax return for CHF 39 per declaration per tax year, with full preparation currently for seven cantons; you still file through your canton's official portal. All six answers are on the data-protection page and the security page before you create an account. If you first just want to know what your municipality means for your tax bill, that works with no upload and no account in the free tax comparison. And what other tools exist, with prices and sources, is in the 2026 comparison of software and services.