How the subsequent ordinary assessment works in Aargau
On a B permit, your employer deducts tax from your salary every month. In certain cases, Aargau still requires a normal tax return. The procedure is called the subsequent ordinary assessment (nachträgliche ordentliche Veranlagung, NOV). The tax at source you have already paid is credited against cantonal, municipal and federal taxes without interest. The assessment itself is made by the tax commission of your municipality.
The federal framework is the same in every canton: a tax return is mandatory once your gross salary in a tax year is CHF 120,000 or more (federal ordinance on tax at source, Art. 9). For married couples, each salary counts on its own. If you arrive in Switzerland during the year, only your regular salary is scaled up to twelve months, while one off payments such as a bonus count in full. And once you are in the NOV, you stay in it until tax at source ends for you. The rules of all cantons side by side are in our guide on when you must file a tax return while taxed at source.
Aargau has one special feature: a flat tax on securities income. This article shows how it relates to the tax return. Tax year 2026, checked October 2026.
Who has to file a tax return in Aargau
The canton lists the criteria on its page «Quellensteuern abwickeln» (handling tax at source), in the section on the NOV for residents of Aargau:
- Salary of CHF 120,000 or more. A gross annual salary from employment of «mindestens Fr. 120'000», meaning at least CHF 120,000. The salaries of married couples are not added together. The Aargau ordinance on tax at source (SAR 651.712) refers to the same federal amount in section 9 (1).
- Income not taxed at source of CHF 3,000 or more. This covers, for example, income from securities or property of «mindestens Fr. 3'000».
- Assets. The canton names «steuerpflichtiges Vermögen» (taxable assets) of at least CHF 130,000 for single people and CHF 260,000 for married couples. The page does not say which deductions are part of these taxable assets. If your assets after debts are at or above this amount, we therefore check your case individually.
- Withholding tax. If you reclaim withholding tax, the canton says this also leads to a subsequent ordinary assessment.
Below CHF 120,000 you have to act yourself: under section 118 (3) of the tax act, you request the tax return forms from the responsible office by 31 March of the following year.
The Aargau thresholds 2026 and their source
| Criterion | Single | Married | What it means for you |
|---|---|---|---|
| Gross salary | CHF 120,000 or more | CHF 120,000 or more for one of the two | Mandatory |
| Income not taxed at source | CHF 3,000 or more | CHF 3,000 or more | Mandatory |
| Taxable assets | CHF 130,000 or more | CHF 260,000 or more | Assets after debts at or above the amount: checked individually |
| Reclaiming withholding tax | No minimum amount stated | No minimum amount stated | Ordinary assessment |
Source: canton of Aargau, page «Quellensteuern abwickeln», NOV section, accessed in October 2026 (the page shows no publication date); ordinance on tax at source SAR 651.712, as at 1 January 2026, section 9 (1).
The amounts for income and assets come from the canton's website, not from the tax act or the ordinance. Section 118 (1)(b) of the tax act only says that assets and income not taxed at source lead to an assessment.
Flat tax instead of a tax return
Section 9 (2) of the Aargau ordinance on tax at source sets out its own route for securities: if your securities do not exceed the wealth tax allowance (section 54 of the tax act), the canton charges a flat 15 percent tax on your securities income. If you do not agree with that, you can ask for an ordinary assessment.
The website and the ordinance are worded differently near the line. The ordinance talks about your securities and about the allowance «not being exceeded»; there the allowance rises for every child with a child deduction. The website talks about taxable assets, uses «at least» and mentions no extra amount for children. Exactly at the line or with children, the two can lead to different results. If you are in this range, it is best to talk your case through with us.
Application, form and deadline in Aargau
- Mandatory case below CHF 120,000: request the tax return forms by 31 March of the following year (tax act, section 118 (3)). For the tax year 2026 that means by 31 March 2027.
- Voluntary application: by 31 March of the following year to the cantonal tax office (ordinance on tax at source, section 10 (1)). An application cannot be withdrawn. According to the page «Quellensteuerpflichtige Personen» (published 9 September 2026), the application «NOV 2026 ganzjährig» is available from 1 January 2027 and has to be submitted online by 31 March 2027 at the latest, through the canton's Smart Service Portal.
- Moving abroad: you submit the application at the latest when you deregister (tax act, section 118a (3)). For 2026 that is the application «NOV 2026 unterjährig», the only one open until 31 December 2026.
- Responsible office: Kantonales Steueramt Aargau, Sektion Quellensteuer, Tellistrasse 67, 5001 Aarau. The assessment itself is made by the tax commission of your municipality.
Important: once you are in the NOV, you stay in it until tax at source ends for you (tax act SAR 651.100, section 118b (1)). Without the NOV, tax at source replaces the ordinary taxes on your employment income, and no additional deductions are granted afterwards (section 118b (3)).
Choosing the ordinary assessment voluntarily: is it worth it?
According to the canton, applying for the NOV opens deductions such as actual professional expenses, pension fund buy ins, pillar 3a contributions, education and training costs you pay yourself, childcare by third parties, maintenance payments, debt interest, and costs related to illness or disability. The tax rate of your municipality also plays a role. The numbers on pillar 3a are in our article on pillar 3a with a B permit, the key deductions in the canton in tax optimisation in Aargau.
Keep the lock in in mind: once you apply, you file a tax return every year until tax at source ends for you. In a later year the result can be higher than tax at source.
Example from Aargau
Sara is single, lives in Aargau and earns a gross salary of CHF 104,000. Her savings account and securities add up to CHF 55,000, with no debts. Her interest and dividends come to CHF 1,100 in 2026.
- Salary: below CHF 120,000, so no duty from the salary.
- Income not taxed at source: CHF 1,100, below CHF 3,000.
- Assets: CHF 55,000, below the canton's CHF 130,000.
Result: Sara does not have to file a tax return for 2026. If her securities stay within the allowance, the flat 15 percent tax applies to their income. If she pays into pillar 3a or wants the withholding tax on Swiss dividends back, she can ask for the ordinary assessment, with the lock in until tax at source ends for her.
Check your case in the calculator
The B permit calculator asks for your civil status, salary, assets and income not taxed at source, and shows whether a tax return is mandatory in Aargau, needs a closer look, or could be worth filing voluntarily.
Every case is different
Whether you have to file depends on your civil status, your salary, your assets after debts and the type of income you receive. This article sets out the rules for the tax year 2026 and one simplified example; it does not replace individual advice. If you would rather not do the tax return yourself, everything about our tax return service in Aargau is on our canton page.