Solothurn Corporate & Capital Tax - Forms & Deadlines
Last updated: 14 Dec 2025
Solothurn Corporate & Capital Tax — Forms & Deadlines
What companies need to file for the Canton of Solothurn’s corporate profit tax and capital tax: who is required to file, how to use eTax Solothurn JP for juristic persons, key documents, filing deadlines, extensions, assessments, payments, interest, and tax clearance in practice.
Who Must File
- Resident companies with statutory seat or effective place of management in the Canton of Solothurn must file a combined corporate income and capital tax return (Steuererklärung für juristische Personen) for each tax year.
- Nonresident entities with a taxable nexus in Solothurn — for example, a permanent establishment or Solothurn-situs real estate — generally file a limited Solothurn corporate tax return covering their local taxable base.
- All legal forms treated as “juristic persons” under Solothurn tax law (e.g. AG, GmbH, cooperative, certain foundations and associations) file, even in loss years or where only minimum capital tax is due.
- Groups with multiple Swiss entities file separate returns for each legal entity with a Solothurn tax nexus; group information is provided via attachments and transfer pricing documentation rather than a consolidated return.
Key Forms & Documents (Solothurn Corporate & Capital Tax)
| Item | Purpose | Typical contents |
|---|---|---|
| Corporate tax return (juristic persons) | Main filing for Solothurn corporate income tax and capital tax, prepared and submitted electronically via eTax Solothurn JP. Paper forms or printouts are used only in exceptional cases (e.g. older tax periods or special situations). | Identifying data; tax period; reconciliation from accounting profit to taxable profit; loss carryforwards; capital tax base; information on participation relief and special regimes under Solothurn and federal tax law. |
| Financial statements | Basis for profit and capital tax assessment; must reconcile to the tax return. | Signed annual report, statutory balance sheet, income statement, notes, appropriation of profits, audit report (if applicable), and prior-year comparatives. |
| Tax reconciliation & schedules | Explains adjustments between statutory accounts and taxable result and documents capital tax base. | Add-backs and deductions; depreciation schedules; provisions; hidden equity analysis; participation deduction calculation; allocation of equity to the Solothurn tax nexus. |
| Group & related-party documentation | Supports transfer pricing, interest conditions and intra-group services. | Group structure chart; intercompany agreements; transfer pricing documentation; overview of loans and guarantees; rulings, if any. |
| Extension request | Requests additional time to file beyond the ordinary deadline. In Solothurn, extension requests for tax returns (including juristic persons) are made via the official online form for deadline extensions or by written request to the Steueramt. | Tax period; company details; reference or identification code; proposed new filing date; reasons (e.g. late financial close, audit delays, restructuring). |
| Payments & account extracts | Evidence of advance payments and final settlement to match assessments. | Advance tax invoices; payment confirmations; reconciliation of assessed tax with instalments; interest and refund statements. |
eTax Solothurn allows corporate taxpayers to complete and submit their tax returns online. For current tax periods, juristic persons use the eTax JP module accessible via the cantonal portal; guidance and annual instructions (Wegleitung JP) are provided in the eTax help centre. For older years, separate download software (SolothurnTax Jur) remains available.
Deadlines & Extensions
Standard timing
For companies (juristische Personen) in Solothurn, the ordinary filing deadline for the corporate tax return is generally 30 June of the year following the tax period for calendar-year companies. For example, a company with year-end 31 December 2024 ordinarily files the 2024 return by 30 June 2025, unless the tax office specifies a different date in its filing notice.
The Steueramt des Kantons Solothurn sends a tax package and/or online access information (including eTax login details) each year. Where no package has been received but a Solothurn tax nexus exists, companies should contact the corporate tax unit to clarify registration and deadlines.
Extensions
Solothurn allows deadline extension requests for tax returns via a dedicated online form or by email/post to the Steueramt. For many tax periods, an initial extension can be obtained at low or no cost, with the possibility of further extensions (often subject to justification and, in some cases, a fee) up to late autumn.
Extension requests must be submitted before the ordinary deadline or any previously granted extended deadline. Late or missing returns can trigger reminders, estimated assessments and penalties. An extension to file does not automatically extend the time to pay; interest may accrue on unpaid balances even where the filing deadline has been extended.
Assessment, Payment & Interest
- Assessment. After the return is processed, the Steueramt des Kantons Solothurn issues an assessment decision covering cantonal, communal and direct federal tax components for the company, including capital tax.
- Advance payments. Solothurn typically issues advance tax invoices based on prior periods or estimated current income and capital. These advance payments are credited against the final assessment; companies can request adjustments where expected results differ significantly from the previous period.
- Payment mechanics. Taxes are paid via the channels indicated on the invoices and assessment (e-banking, payment slip, etc.). The company should always use the correct reference number to ensure allocation to the right tax period.
- Interest & penalties. Interest is normally charged on late payments; in more serious cases penalties can be imposed for late filing, incomplete disclosure or tax evasion. Where liquidity is tight, companies may request instalment plans (Ratenzahlung) or payment arrangements from the tax office.
- Objections/appeals. The assessment letter specifies the objection (Einsprache) deadline and procedure. Objections must be submitted in writing within this period and supported by explanations and evidence (e.g. corrected financials, alternative calculations).
Tax Clearance & Commercial Register (Corporate Changes)
- Significant corporate events such as dissolution, liquidation, mergers, de-mergers or migrations of seat often require tax clearance from Solothurn before the commercial register completes the registration or before a move to another canton.
- For liquidations, the tax office typically assesses income and capital tax up to the liquidation date and may require interim or final returns. Distributions to shareholders can trigger additional income or withholding tax consequences.
- In cases of seat relocation to or from Solothurn, the company must coordinate opening or closing balance sheets for tax purposes and agree on the allocation of hidden reserves and equity between cantons.
- For corporate restructurings under Swiss tax neutrality rules, advance tax rulings are frequently used to secure treatment at Solothurn and federal level.
Submission Checklist
| Document | Included? | Notes |
|---|---|---|
| Completed corporate tax return (Solothurn, juristic persons) | ⬜ | Prepared and submitted via eTax Solothurn JP for the correct tax year (or, exceptionally, on the official paper forms). |
| Signed financial statements & audit report (if applicable) | ⬜ | Balance sheet, income statement, notes, appropriation of profits. |
| Tax reconciliation profit → taxable profit | ⬜ | Adjustments for non-deductible expenses, provisions, depreciation, etc. |
| Capital tax base reconciliation | ⬜ | Equity per accounts, hidden equity and allocation to the Solothurn tax nexus. |
| Schedules for participation relief / exemptions | ⬜ | Dividend and capital gains details; holding percentage; acquisition cost. |
| Group and related-party overview | ⬜ | Structure chart, intercompany contracts, transfer pricing documentation. |
| Supporting documentation for major items | ⬜ | Loan agreements, valuations, impairment tests, restructuring documents. |
| Confirmation of advance tax payments | ⬜ | To reconcile assessments and check interest/penalties. |
| Extension request (if filing after ordinary deadline) | ⬜ | Online or written deadline extension request submitted before the existing deadline. |
| Signature or confirmation by authorised signatories | ⬜ | For paper filings, the tax return must be signed in line with commercial register rules; for electronic submissions, ensure the persons approving the filing correspond to the company’s authorised signatories. |
Where to Submit / Contact
Canton Solothurn Tax Administration — Corporate tax unit (Juristische Personen) handles corporate income and capital tax returns. Returns are typically submitted electronically via eTax Solothurn JP. Where paper is used, returns are mailed to the address stated on the tax package or on the cantonal website, together with the signed forms and financial statements.
As at 2025, the central contact details for corporate taxpayers are:
Steueramt des Kantons Solothurn — Juristische Personen
Werkhofstrasse 29c
4509 Solothurn, Switzerland
Tel: +41 32 627 87 42 · Email: sekretariat-jp@fd.so.ch
Need help with your Solothurn corporate or capital tax filings? Our Swiss corporate tax work for Solothurn is handled by Sesch TaxRep GmbH, Switzerland. For a fixed-fee engagement, please contact us with your company details, latest financial statements and tax period.
FAQs
What is the filing deadline for companies in Solothurn?
For most juristic persons in Solothurn, the ordinary deadline is 30 June of the year following the tax period (for example, 30 June 2025 for a 2024 calendar-year company), unless the tax office sets a different date in its filing notice. Extensions can usually be obtained via the official deadline-extension process, but the request must be made before the original due date.
Can I file the corporate tax return electronically?
Yes. Solothurn provides eTax Solothurn JP for juristic persons. You prepare the corporate tax return electronically and submit it via the cantonal portal. Supporting documents can be uploaded as attachments; in some cases, the tax office may still ask for specific paper documents.
Can I extend time to pay as well as to file?
An extension to file does not automatically extend the time to pay. If you expect to pay late or require instalments, you should contact the Steueramt des Kantons Solothurn proactively to discuss payment arrangements. Interest may accrue on outstanding balances regardless of filing extensions.
Do small or loss-making companies still have to file?
Yes. All juristic persons with a Solothurn tax nexus normally must file a corporate tax return, even if they have low turnover, losses or only minimum capital tax to pay. The return documents the loss position and keeps loss carryforwards alive.
Who should sign the Solothurn corporate tax return?
For paper filings, the tax return must be signed by persons authorised to represent the company, typically board members or directors registered in the commercial register with individual or joint signing authority. Representatives such as fiduciaries may sign in addition, but this does not replace the company’s own signature requirements. For electronic submissions via eTax Solothurn, ensure that the persons approving the submission correspond to the company’s authorised signatories as reflected in internal corporate documentation.
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