Tax guides
Modern Swiss timber and glass facade under an overcast sky, with a single red window frame

Tax guides

Which documents the 2025 Swiss tax return needs in Zurich and Aargau

A documents checklist for the 2025 tax return in the cantons of Zurich and Aargau: what you need, what the canton wants to see with the return, and what you only keep.

Updated on 08.10.2026 · 7 min read

For the 2025 tax return, an employed household in the cantons of Zurich and Aargau needs five groups of documents: the salary certificate (Lohnausweis) from every employer, the certificate of pillar 3a contributions, the bank's interest and tax statements, the receipts behind any deductions (medical costs, childcare, further education, donations) and, with debts or a home of your own, the interest statements and property paperwork.

Only part of that goes to the tax office. Both cantons separate what travels with the return from what you produce when asked, but they don't draw the line in the same place, least of all for medical costs.

Not covered here: the self-employed, income from abroad, and the cantons of Lucerne, Solothurn, Bern, Zug and Schwyz.

Needing a document isn't the same as sending it

A till receipt sits in a drawer until the appliance breaks. Nobody asks to see it before then, but without it there's no warranty. Much tax paperwork works the same way: you need it to enter the right number, and you show it only if the tax office asks.

Zurich's guide turns that into a rule. Receipts behind your lists and forms are to be sent with the return only where that is expressly required («nur dann ... wenn dies ausdrücklich verlangt ist»). Its examples are receipts for property costs and donations, which follow on request during the assessment. What always goes in, the guide lists item by item, starting with the salary certificates.

Aargau keeps one list, the documents to have in front of you before you start. Its guide points back to that list when it says paper submissions should be copies (the salary certificate is the one original).

Which documents belong to which part of your life?

AreaDocumentCanton ZurichCanton Aargau
SalarySalary certificate from every employerEnclose, with its enclosuresProves every salary; exempt from "copies only"
Pillar 3aCertificate of contributionsEncloseEnclose
Bank, securitiesInterest statement, tax statementSecurities register; the tax statements it cites are enclosedFull tax statement with the securities register
Medical costsInvoices, insurer's summaryForm, with the insurer's summaryCopies of receipts; a blanket insurer summary isn't enough
ChildcareDaycare invoicesA listA list plus copies of receipts
Further educationCourse invoicesFormA list plus receipts
DonationsDonation receiptsA list; receipts on requestEnclosing not required; may be requested later
Debts, mortgageInterest and debt statementSchedule of debts with creditor, address, interest rateSchedule of debts, debts evidenced; submit interest receipts
Property maintenance, actual costsTradespeople's invoicesA list; receipts on requestOn the list of documents; invoices not addressed

As of: the table reflects the two cantons' guides to the 2025 tax return. For a later tax year, that year's guide applies.

Which of these deductions may be relevant for you depends on your circumstances.

The salary certificate is the one document both cantons want without conditions (two of them after a job change). Zurich asks you to state any gap in employment expressly, so it's clear that no income certificate was forgotten. Aargau wants the reasons where, for some period, you received neither a salary nor replacement income.

For securities, Zurich's online return can read in the eSteuerauszug, a tax statement with a barcode. What goes into the register, and at which value, is in the article on the securities register.

Neither list names the health insurer's premium statement. In Aargau the deduction for insurance premiums is a flat amount. In Zurich you enter the premiums you paid, less any premium reduction, so you'll want the figures from the policy or the annual statement.

Last year's return isn't on either list, though it shows which accounts, policies and debts you declared a year ago.

Where Zurich and Aargau part ways

For medical costs, Zurich wants its completed form («Aufstellung über Krankheits- und Unfallkosten») and asks you to send the health insurer's summary along with it. Aargau wants the costs proven with copies of receipts and adds that a blanket summary from the health insurer doesn't meet that requirement («genügt diesen Anforderungen nicht»).

Childcare follows the same pattern; the amounts per canton are in the article on childcare costs.

Donations run the other way: Aargau doesn't require receipts to be enclosed.

Online or on paper

In Zurich's online return, an upload field appears as soon as you enter an item for which supporting documents can be submitted. The field tells you whether the document is mandatory or optional, and the return can't be submitted without the mandatory ones. For the online return the canton also asks you to keep every document until the assessment is final, submitted or not.

In Aargau, supporting documents can go in digitally, on paper, or as a mix of both.

Neither canton's 2025 guide names a retention period for private individuals.

When a document is missing

Whoever issues a document is also where you turn when it's missing:

  • Salary certificate: employers are obliged to issue one that lists all payments, the job you left included.
  • Pillar 3a: the certificate comes from the bank foundation or the insurer.
  • Tax statement: the bank generally produces one only when you order it.
  • Health insurer: ask, and many insurers will send an overview of the year's costs and premiums.
  • Forms: from the municipal tax office or the canton's website.

What's in Jana and Luca's pile

Jana and Luca are married, both employed, and rent a flat in Winterthur. Luca changed jobs in summer 2025, their daughter goes to daycare, both pay into a pillar 3a, Jana has a small securities account, and they gave to two charities.

Their pile for the 2025 return: three salary certificates (one for Jana, two for Luca), two 3a certificates, the interest statement for the joint account, the tax statement for Jana's securities, the year's daycare invoices and two donation receipts.

Zurich's list asks them to enclose the three salary certificates, the form for work expenses and insurance premiums, the two 3a certificates, a statement of the childcare costs and a list of the donations. The securities register goes in with the tax statement. The donation receipts stay in the folder until the tax office asks.

Move the two of them to Baden and the envelope changes. Copies of the daycare invoices join the childcare statement, and the donation receipts don't have to be enclosed. Salary and 3a certificates go in there too. The pile at home is the same.

From the pile to the return

That pile is where TaxWize starts. You can upload the salary certificate, 3a certificate, health insurance statement, eSteuerauszug and invoices. Where TaxWize reads a document with AI, the AI is hosted in Switzerland, and you can check and correct every value the AI reads. The tax calculation is a deterministic rule set. TaxWize costs CHF 39 per tax return and tax year, and you still file with your canton.

In the canton of Zurich, 30.11.2026 is the latest ordinarily granted date for the 2025 return. The other cantons' dates are in the article on deadline extensions. For a first estimate of what your income costs in tax in your municipality, there's the tax comparison tool.

Sources

Frequently asked questions

Which documents do I need for the 2025 Swiss tax return?
As an employee in the canton of Zurich or Aargau you need the salary certificate (Lohnausweis) from every employer, the certificate of your pillar 3a contributions, the bank's interest and tax statements, and the receipts behind the deductions you claim: medical costs, childcare, further education, donations. With debts or a home of your own, add the interest statements and the property paperwork.
Do I have to send every receipt with the tax return?
No. In Zurich, receipts behind your lists and forms go in only where the guide expressly asks for them; receipts for property costs and donations follow on request. In Aargau, donation receipts needn't be enclosed, while the 2025 guide does ask for copies of receipts for childcare, further education and medical costs. The salary certificate goes in under both.
Is my health insurer's summary enough to prove medical costs?
It depends on the canton. Zurich asks you to send the insurer's summary together with its completed form for medical and accident costs. Aargau asks for copies of the receipts for the 2025 return and states that a blanket summary from the health insurer doesn't meet that requirement. Whether the deduction has any effect for you also depends on the deductible threshold.
How long do I need to keep my tax documents?
For the online return, Canton Zurich asks you to keep every document until the assessment is final, whether or not you submitted it; it can still request them until then. Neither canton's 2025 guide names a retention period for private individuals. Aargau's guide does say that donation receipts you didn't enclose can be requested afterwards.
What do I do if my salary certificate is missing?
Ask the employer for it, including a former one. Aargau's guide states that employers are obliged to issue a salary certificate listing all payments. After a job change you need the certificate from each job you held in 2025. Zurich also asks you to state any gap in employment expressly in the return.

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