Back to all articles
Hands sorting green apples in a wooden crate, with a single red apple among them

Perspectives

Does AI check your Swiss tax return? What the cantons say in 2026

In Solothurn, a system of rules and machine learning can trigger an automated tax assessment. Schwyz spells out where the limits are. Here's the overview.

Published on 17.09.2026 · 7 min read

It depends on the canton. Of the seven cantons TaxWize covers, only Solothurn describes using such a system in its 2025 filing guide so far. There, a system built on fixed rules and machine learning can estimate whether the tax office needs to take a closer look at your return. If it doesn't, the assessment (the tax office's decision setting your taxable income and your tax) is issued automatically, and the notice says so.

A second canton has put in writing what AI can and can't do in a tax office today. In a decision dated 01.09.2026, the Schwyz cantonal government states that, with current technology, AI can only play a supporting role (checking data for plausibility, spotting anomalies). In the government's view, it can't assess or correct figures and receipts for tax purposes on its own.

How a system like this sorts returns

Apples roll along a conveyor in a fruit packing shed. The machine doesn't cut any open or taste them. All it decides is which apples roll straight through and which ones someone picks up.

The Schwyz government describes the technology in similar terms, in two stages. The first runs on fixed rules. A module in NEST, the assessment software Schwyz uses, compares the amounts you declare with predefined check values and flags deviations. Depending on the size of the deviation, the tax office examines the case in depth, only on the essential points, or not at all. Schwyz has used this rule-based check since the 2007 tax period.

The second stage is what people now call AI. A learning module looks for statistical patterns across submitted tax returns (earlier tax periods included). It also flags which cases a person should examine more closely, and it only runs after the rule-based check. Schwyz plans to use an AI module of this kind.

The government puts the difference like this: classic automation is based on clearly defined rules and delivers reliable results, while a learning system works with probabilities, so the same input can produce different outputs.

What applies in Solothurn

In a few sentences, Solothurn's guide also says what the system draws on: the return you submitted, existing declaration and assessment data from the canton, and a set of criteria defined by the tax office. From that, it forecasts whether further investigation is needed.

The sentence that matters most to you closes the passage: assessment notices produced with the system are marked accordingly. The guide doesn't show what the marking says.

For comparison, take a canton outside the seven. In June 2026, Basel-Stadt's government proposed an amendment to its tax act to build a learning system into its assessment software. It's meant to go live in 2027 for the 2026 tax period and run exclusively on cantonal servers, with more complex returns still handled by hand. As examples of cantons already using such a system, Basel-Stadt names Solothurn, Obwalden and Nidwalden.

The seven cantons at a glance

I searched the 2025 guides of all seven cantons for any mention of algorithmic or learning systems.

CantonWhat the canton publishes
Solothurn2025 guide: assessment may use a system of rules and machine learning; automated where no further investigation is needed; such notices are marked
SchwyzCantonal government, 01.09.2026: rule-based check in use, use of an AI module planned. Nothing in the 2025 guide
Aargau, Zurich, Lucerne, Zug, BernNothing in the 2025 guide

A missing mention doesn't mean nothing is automated in those cantons. It only means the guide doesn't describe it.

Can you challenge an automated assessment?

Yes. You can file a written objection (Einsprache) against an assessment notice within 30 days of receiving it. Both the Federal Act on Direct Federal Taxation and the Tax Harmonisation Act say so, and neither distinguishes by how the notice was produced. Basel-Stadt states explicitly that, under its planned system, an objection gets your case reviewed by tax administration staff. Solothurn's guide doesn't address this in that passage.

An objection does reopen the whole case, though. The tax office can reset every tax factor and, after hearing you, change the assessment to your disadvantage. How the 30 days are counted is covered in the piece on discretionary assessments and objections.

I'd read an automated notice exactly the way I'd read any other: line by line, next to the return I filed. Whether an objection is worth it depends on what differs and why.

Why Schwyz is being careful

Three of the reasons the Schwyz government gives for its caution affect every taxpayer directly.

The first is oversight. According to the government, a learning system usually doesn't document how it reached a result in a way anyone can follow. In its view, an assessment meant to follow the law as closely as possible therefore needs people to review what the AI produces, for now. The decision calls this "human in the loop".

The second is tax secrecy. A system like this needs a very large amount of tax data to learn from, and that data is protected. The government says this strongly limits AI run by outside providers and leaves only those with the highest data protection standards, or in-house solutions that rule out any data transfer.

The third is the principle of legality. In the government's view, an AI that assesses returns on its own needs an explicit basis in law, and existing provisions on automated procedures aren't enough. Schwyz plans to add a provision on the use of AI in its next tax act revision. The decision doesn't judge Solothurn's system.

At TaxWize, rules and AI are kept apart: the tax calculation is a fixed rule set that returns the same number for the same inputs. Reading your uploaded documents uses AI, and every value the AI reads can be checked and corrected.

What's still a political question

The Schwyz answer responds to a postulate (a formal request for the government to examine an issue) from cantonal parliamentarian Dr. Thomas Grieder and 15 co-signatories. They point to the extra workload individual taxation will bring the tax administration, and want the government to examine how AI could automate processes and take repetitive tasks off staff.

In principle, the government supports AI models provided they're robust, accurate, transparent and traceable, with a basis in law and sound information security. But it doesn't share the view that a large part of the work could already be done with AI on top of today's automation, and it asks the cantonal parliament not to adopt the postulate. For the years from 2032, it expects little relief from AI, because a reliable data basis for the new individual tax returns first has to be built up.

One remark reaches beyond Schwyz. The more uniform the tax process, the more of it can be automated, the government writes, and that takes political willingness to standardise, with fewer deductions as one example. Which simplifications lawmakers are ready for is, in its words, a question for politics. The cantonal parliament has the final say on the postulate.

Sources

Frequently asked questions

Does an AI decide on my tax return at the tax office?
It depends on the canton. In Solothurn, a system combining fixed rules and machine learning can estimate whether a return needs closer investigation. If it doesn't, the assessment is issued automatically. The Schwyz cantonal government states that, with today's technology, AI can only support the process and doesn't assess figures and receipts for tax purposes on its own.
How can I tell whether my assessment was automated?
In Solothurn, from the notice itself: the canton's 2025 guide says assessment notices produced with its algorithmic system are marked accordingly. It doesn't say what the marking reads. The 2025 guides of Aargau, Zurich, Lucerne, Zug, Bern and Schwyz contain no mention of such a system. That doesn't mean nothing is automated there; the guides just don't describe it.
Can I object to an automated assessment?
Yes. You can object in writing within 30 days of receiving an assessment notice. Basel-Stadt says explicitly that, under its planned system, an objection gets your case reviewed by tax administration staff. In objection proceedings the tax office can reset every tax factor, including to your disadvantage, so whether an objection is worth it depends on what differs.
Does my tax data go to outside AI providers?
Basel-Stadt says its planned system runs exclusively on cantonal servers. Schwyz writes that tax secrecy strongly limits externally operated AI and leaves only providers with the highest data protection standards or in-house solutions with no data transfer. Solothurn's guide doesn't say where its system runs.
Which cantons use AI in tax assessment?
Basel-Stadt names Solothurn, Obwalden and Nidwalden as examples of cantons already using such a system, and plans to introduce it itself from 2027 for the 2026 tax period. Schwyz plans to use an AI module. Of the seven cantons TaxWize covers, only Solothurn describes its use in its 2025 guide. Whether the others use such a system, their guides don't say.

Related guides

Keep your deductions in view

TaxWize reads your documents, surfaces deductions that may be relevant, and prepares your tax return for filing. CHF 39 per tax return per tax year.

Explore TaxWize