How to declare your income as a sole proprietor in 2026: deadlines, forms, and filing methods

Filing a tax return as a sole proprietor seems like a simple procedure only at first glance. In reality, entrepreneurs face dozens of specific questions: which form to use, when to file their return for their tax group, and how to make sure the tax authority has accepted it.

In this article, we’ve compiled all the basic information in one place: who files which tax return, what deadlines apply to different single-tax groups, which services can be used to file returns, and what mistakes to avoid.

Which sole proprietors file tax returns, and what factors determine this?

All sole proprietors under the simplified tax system must file a tax return. The filing procedure depends on the single-tax payer’s group and the reporting period.

The main factors are:

• single tax group;
• presence or absence of income;
• obligation to file Appendix 1 for the Unified Social Tax (UST);
• method of filing reports.

It is important to understand that even if you had no income during the reporting period, in many cases you are still required to file a tax return.

What tax return do sole proprietors in groups 1, 2, and 3 file?

Individual entrepreneurs under the simplified tax system use the single-tax payer tax return, but the procedure for filing it varies depending on the group.

Before filing your tax return, you should check the following:

• the validity of the tax return form;
• the correctness of the selected category;
• the amounts of income received;
• the inclusion of the required attachments.

Deadlines for filing individual entrepreneur tax returns in 2026

The deadline for filing the tax return depends on the single tax group and the reporting period. This determines how often a business owner must report to the tax authorities: once a year or quarterly.

When to file a tax return for a Group 1 sole proprietor

Entrepreneurs in Group 1 must file a single tax payer declaration for individual entrepreneurs (Form F-0103407) based on the results of the calendar year. The declaration must include income received and other figures specified in the reporting form.

Even if no business activity actually took place during the year or no income was earned, the obligation to file the return may still apply.

When to file a tax return for a Group 2 sole proprietor

An annual reporting period has also been established for Group 2 sole proprietors. The tax return for a single-tax payer—an individual entrepreneur (Form F-0103407)—covers the entire calendar year and is filed after the year ends.

In practice, entrepreneurs often put off filing their returns until the last few days. However, it is important to take into account potential technical issues with electronic services and allow time to correct errors in case the tax authority does not accept the document on the first attempt.

When to file a tax return for a Group 3 sole proprietor

Group 3 sole proprietors file reports more frequently—at the end of each quarter. This means that four single-tax payer returns (Form F-0103309) must be filed throughout the year.

Since reports are filed regularly, it is especially important for Group 3 entrepreneurs to keep track of their income throughout the quarter, rather than collecting data immediately before filing the return.

When determining filing deadlines, you should refer to the tax calendar for the current year. If the last day for filing falls on a weekend or a holiday, the deadline may be extended in accordance with the law.

Is Appendix 1 / Unified social contribution required?

In some cases, Appendix 1, which contains information on the calculation and payment of the unified social contribution (USC), must be submitted along with the sole proprietor’s tax return.

Whether you need to submit Appendix 1 depends on your tax group and your obligation to pay the USC.

Before preparing the tax return, you should check the following separately:

• whether you are required to report information on the USC;
• whether you are eligible for an exemption from paying the USC;
• whether you need to complete Appendix 1 for this specific reporting period.

Not all sole proprietors are required to submit Appendix 1 regarding the USC along with their tax return. Pensioners and people with disabilities who receive a pension or social assistance, as well as entrepreneurs who have taken advantage of the military exemption from paying the Unified Social Tax (USC), are exempt from this requirement. The exception is when a sole proprietor voluntarily pays the USC for themselves: in that case, Appendix 1 must be submitted.

The rules regarding the Unified Social Tax (UST) are subject to change, so it is advisable to check the current requirements of the State Tax Service before filing the tax return.

Reasons for filing a sole proprietor tax return

Today, most business owners file their tax returns electronically. This allows them to sign the document with a digital signature, submit it to the tax authority, and receive confirmation of receipt without having to visit the tax office in person.

There are several options available for filing a tax return:

• the taxpayer’s electronic account;
• the Diya portal or app;
• electronic reporting services;
• submission on paper in person or by mail (in cases provided for by law).

Regardless of the method of submission, after sending the tax return, you must obtain a receipt confirming its acceptance. This receipt confirms that the return has been successfully registered by the tax authority.

How to file a tax return through the Electronic Portal

The Taxpayer’s Electronic Account is the State Tax Service’s official service for filing tax returns electronically.

The main advantage of the Electronic Taxpayer Portal is the direct exchange of documents with the tax authority. At the same time, users must independently navigate the reporting forms, verify that they are filled out correctly, and monitor the status of submitted documents.

How to file a tax return through Diya

For certain categories of entrepreneurs, it is possible to file a tax return through Diya. The service automates part of the process and allows you to complete your tax return using a simplified interface.

Before submitting, check whether Diya supports the required type of tax return and your taxpayer category. The service’s functionality may change depending on updates to government e-services.

How to file a tax return through Vchasno.Zvit

When filing tax returns, business owners typically face more than just filling out the return itself. It is equally important to choose the correct form, submit the document on time, and verify that the tax authority has accepted it.

In Vchasno.Zvit, these steps are all consolidated into a single platform. Entrepreneurs can prepare their tax returns, sign them with a digital signature, and track the status of their submission without having to switch between different services.

The service offers:

✅ creating and filing tax returns online;
✅ signing documents with a digital signature;
✅ tracking the status of submitted returns;
✅ receiving acknowledgments from the State Tax Service;
✅ storing a history of filed returns;
✅ a tax calendar with current deadlines for filing returns and paying taxes;
✅ reminders about upcoming important filing dates to help you avoid missing deadlines;
✅ technical support regarding the service’s operation;
✅ consulting support regarding filing and the use of electronic documents.

This approach is particularly convenient for entrepreneurs who file their own returns and want to manage the entire filing process in one place.

Checklist before submitting your tax return

Before submitting your tax return to the tax office, check the following:

1. You have selected the tax return form that applies specifically to your category of sole proprietor.
2. The tax return specifies the correct reporting period.
3. All income has been reported in full and matches your accounting records.
4. If your situation requires Appendix 1 or other appendices, they have been attached to the tax return.
5. Your digital signature is valid and has not expired at the time of signing the documents.
6. The entrepreneur’s full name, RNO-KPP, and other details are entered correctly.
7. After submission, you received Receipt No. 1 confirming the document’s delivery.
8. After the tax return was processed, you received Receipt No. 2 confirming its acceptance by the tax authority.
9. A copy of the submitted tax return and the receipts has been saved for your personal records.

How to check if your tax return has been accepted

The fact that a tax return has been submitted does not necessarily mean it has been successfully accepted. After submitting an electronic tax return, you must receive:

Receipt No. 1 — confirmation that the document has been delivered to the tax authority.

Receipt No. 2 — confirmation of acceptance or a notice of rejection. It is Receipt No. 2 that confirms the outcome of the return’s processing.

If you receive an error message, you must correct the return and resubmit it. In Vchasno.Zvit, receipt statuses are displayed in a convenient format, so entrepreneurs can quickly check whether their reports have been accepted. If errors occur during the submission or verification of a declaration, technical support specialists will help identify the cause and suggest possible ways to correct it.

What happens if you miss the filing deadline?

If a tax return is filed late or not filed at all, this may have several consequences. In addition to a fine for missing the filing deadline, the tax authority may:

• impose a fine for failure to file or late filing of the tax return;
• impose administrative liability in cases provided for by law;
• assess tax liabilities on its own if no tax return is filed;
• require the submission of supporting documents or explanations;
• initiate an additional audit or inquiry regarding the sole proprietor’s activities.

Common mistakes when filing an individual entrepreneur tax return

Errors in tax reporting are not always related to complex tax rules. In practice, most problems arise from carelessness when filling out or submitting a tax return.

Among the most common errors are:

• using the wrong tax return form;
• specifying the wrong reporting period;
• failing to submit Appendix 1 when it is required;
• incomplete reporting of income for the reporting period;
• signing the document with an expired or invalid digital signature;
• failing to verify Receipt No. 2, which confirms the tax authority’s acceptance of the return;
• errors in the taxpayer’s identifying information.

Conclusion

Filing a sole proprietor tax return in 2026 depends primarily on the single-tax payer’s group and the reporting period. Before filing, you should check the current tax return form, whether you need to submit Appendix 1 regarding the Unified Social Tax (UST), and the filing deadlines for your group.

You can file the tax return via the Electronic Cabinet, Diya, or electronic reporting services. The most important thing is to obtain Receipt No. 2, which confirms that the tax authority has accepted the document.

If you want to file tax returns, monitor the status of your filings, and store all documents in one place, you can do so through Vchasno.Zvit.