Electronic Signature: How to Get One and When It's Worth It
Not that long ago, most self-employed people got by just fine with a handwritten signature on paper. Today, the situation has changed dramatically. The automatic creation of data mailboxes for OSVČ, the mandatory electronic filing of tax returns, and the growing digitisation of public administration mean that an electronic signature is no longer a luxury — it's a practical necessity. If you're unsure what type of signature you need, where to get it, and how much it will cost, you've come to the right place. This guide will walk you through the entire process from A to Z.
Why should you care about electronic signatures right now?
Since 2023, all OSVČ have had a data mailbox set up automatically. With an active data mailbox comes the obligation to file electronically — tax returns, reports for the Czech Social Security Administration (ČSSZ), and health insurance overviews. For many tasks, you also need to attach an electronic signature to your documents — particularly when signing contracts, submitting applications, or communicating with authorities outside the MOJE daně portal.
What is an electronic signature and what does the law say?
Electronic signatures in European law are governed by the eIDAS Regulation (Regulation of the European Parliament and of the Council No. 910/2014). This regulation applies directly in all EU member states, including the Czech Republic. In Czech law, it is supplemented by Act No. 297/2016 Coll., on trust-building services for electronic transactions.
The eIDAS Regulation distinguishes three levels of electronic signature. Each level offers a different degree of legal certainty and technical security. Let's take a closer look at each one.
Three types of electronic signatures under eIDAS
1. Simple Electronic Signature
A simple electronic signature is the broadest category. It can be practically anything that serves to identify the signing person in electronic form — a scanned signature inserted into a PDF, ticking an "I agree" checkbox on a website, or even a name typed at the end of an email.
Advantages:
- No acquisition costs
- Easy to use
- May be sufficient for routine business relationships
Disadvantages:
- Provides no guarantee of document integrity (the document may have been altered after signing)
- The identity of the signatory cannot be verified
- Can easily be disputed in the event of a disagreement
- Public authorities generally do not accept it
When is a simple electronic signature enough?
A simple electronic signature may be sufficient for routine business communication and internal documents — for example, confirming an order by email, approving an internal process, or signing a straightforward contract between two parties who trust each other. However, in the event of a legal dispute, you would need to prove that the signature actually came from the person in question.
2. Advanced Electronic Signature (Based on a Qualified Certificate)
An advanced electronic signature offers a higher level of security. It must meet four conditions defined in Article 26 of the eIDAS Regulation:
- It is uniquely linked to the signatory
- It is capable of identifying the signatory
- It is created using data that the signatory can, with a high level of confidence, use under their sole control
- It is linked to the signed data in such a way that any subsequent change in the data is detectable
In Czech practice, the term recognised electronic signature is used for communications with public authorities — this refers to an advanced electronic signature based on a qualified certificate. This type of signature is required, for example, when filing through the MOJE daně portal or communicating with the tax office.
Advantages:
- Guarantees the integrity of the signed document
- Enables identification of the signatory
- Recognised by public authorities in the Czech Republic
- Affordable (certificate from approx. 400 CZK/year)
Disadvantages:
- Requires a qualified certificate from a certification authority
- Certificate has a limited validity (1–3 years)
- Not fully equivalent to a handwritten signature
3. Qualified Electronic Signature (QES)
The qualified electronic signature is the highest level of electronic signature under eIDAS. It is an advanced electronic signature that is:
- Based on a qualified certificate for electronic signatures
- Created using a qualified electronic signature creation device (typically a smart card or USB token)
This signature has the same legal effect as a handwritten signature and is recognised in all EU member states.
Advantages:
- Legally equivalent to a handwritten signature
- Recognised across the entire EU
- Highest degree of legal certainty
- Cannot be rejected as evidence in court proceedings
Disadvantages:
- Higher acquisition costs (certificate + qualified device)
- Requires the use of a smart card or USB token
- More complex technical setup
📊Comparison of electronic signature types
When does an OSVČ need an electronic signature?
As an OSVČ, you'll encounter the need for an electronic signature in a wide range of situations. Let's go through the most common ones.
Mandatory electronic filings
Since 2023, when data mailboxes were automatically set up for all OSVČ, electronic filing has been mandatory for:
- Personal income tax returns — if you have an active data mailbox, you must file exclusively electronically
- Reports for the ČSSZ — filed through the ČSSZ ePortal
- Health insurance overviews — mandatory electronically for all OSVČ from 2026
- Control statements and VAT returns — if you are a VAT payer
Important: data mailbox vs. electronic signature
A data mailbox and an electronic signature are two different things. A data mailbox is used for delivering documents, and submissions made through a data mailbox carry the same legal effect as submissions signed with a recognised electronic signature (under Section 18(2) of Act No. 300/2008 Coll.). This means that if you file your tax return through your data mailbox, you do not need a separate electronic signature to do so. However, you will need an electronic signature if you are signing documents outside the data mailbox environment — contracts, powers of attorney, submissions on the MOJE daně portal without a data mailbox, etc.
Signing contracts and business documents
An electronic signature significantly speeds up the process of signing contracts — especially if you work with clients abroad or work remotely. There's no need to print, sign, scan, and post documents.
For routine business contracts (work-for-hire agreements, framework contracts, purchase orders), a recognised electronic signature is generally sufficient. For contracts with greater legal significance (property transfers, notarial acts), a qualified electronic signature may be required.
Communication with health insurance providers and the ČSSZ
For electronic submissions to the ČSSZ and your health insurance provider, you can use either a data mailbox or a recognised electronic signature. An electronic signature is particularly handy for ongoing communication (notifying changes, submitting requests).
Submissions on the MOJE daně portal
The MOJE daně portal allows you to log in and sign submissions in three ways:
- Via your data mailbox
- Via banking identity (BankID)
- Via an electronic signature (recognised)
Where to get a qualified certificate in the Czech Republic
Three qualified trust service providers operate in the Czech Republic and issue qualified certificates for electronic signatures. They are listed in the register maintained by the Czech Ministry of the Interior.
1. PostSignum (Česká pošta, s. p.)
PostSignum is a certification authority operated by the Czech Post. It is the most widely used provider of qualified certificates in the Czech Republic.
How to get a PostSignum certificate:
📋Steps to obtain a PostSignum certificate
- Generate a certificate request — on the postsignum.cz website in the "Certificate Request" section. You will need to install the relevant software or use the online tool.
- Visit a Czech Post contact point — bring your generated request (reference number), a valid ID document, and any other required documents to a Czech Post branch that issues certificates.
- Verify your identity — the operator will verify your identity using your ID document.
- Pay the fee — the certificate fee is paid directly at the branch.
- Download and install the certificate — after identity verification, download the certificate from the PostSignum website using your reference number and install it on your computer.
New option: PostSignum now also offers online certificate issuance without a branch visit — through the Certifikát Online service. You verify your identity using your banking identity (BankID) or a chip-enabled eID card.
PostSignum prices (as of February 2026):
| Product | Validity | Price incl. VAT | |---------|----------|-----------------| | Qualified certificate for electronic signature | 1 year | 440 CZK | | Qualified certificate for electronic signature | 3 years | 990 CZK | | Qualified certificate for electronic seal | 1 year | 440 CZK | | Qualified timestamp | 1 year | from 396 CZK |
2. První certifikační autorita (I.CA)
I.CA is a private certification authority with a long track record on the Czech market. It offers a wide portfolio of certificates, including qualified certificates on smart cards.
How to get an I.CA certificate:
📋Steps to obtain an I.CA certificate
- Visit ica.cz and choose the type of certificate you need.
- Complete the online application — enter your identification details and choose how you want the certificate stored (on your computer or on a smart card).
- Visit a registration authority — I.CA contact points are listed on ica.cz under "Where to find us". Bring a valid ID document.
- Verify your identity and pay — the operator will verify your identity and issue the certificate after payment.
- Install the certificate — download and install it following the instructions on the I.CA website.
I.CA also offers qualified devices (smart cards and USB tokens), which are required for creating a qualified electronic signature (QES). Prices for I.CA qualified certificates start at approximately 500 CZK for a one-year certificate.
3. eIdentity, a.s.
The third qualified provider in the Czech Republic. It focuses primarily on certificates for healthcare and public administration, but also issues qualified certificates for business owners and private individuals.
Which provider should you choose?
For most OSVČ, PostSignum is the most practical choice, thanks to its extensive network of contact points (Czech Post branches across the country) and the lowest prices. If you need a qualified electronic signature on a smart card (QES), consider I.CA, which offers a complete solution including the qualified device. The third option, eIdentity, is better suited to specific sectors such as healthcare.
Step-by-step guide: how to set up your electronic signature
If you've decided to get an electronic signature, the following steps will guide you through the entire process.
What you'll need
Before visiting a contact point, prepare the following:
- A valid ID card (or passport)
- A device with internet access (for generating the request and downloading the certificate)
- Payment for the fee (cash or card, depending on the provider)
Choosing the right type of certificate
📋Decision guide: what certificate do I need?
- Do I only need to sign documents for Czech authorities? → A recognised electronic signature is sufficient (qualified certificate without a qualified device). Price: from 400 CZK/year.
- Do I need a signature equivalent to a handwritten one across the entire EU? → I need a qualified electronic signature (QES) — a qualified certificate + smart card/USB token. Price: from 800 CZK/year + one-time hardware cost.
- Am I only signing routine business contracts with trusted partners? → A simple electronic signature may be enough (free of charge), but for greater legal certainty we recommend at least a recognised signature.
- Do I want to sign documents without visiting a branch? → Use PostSignum's Certifikát Online service (verification via BankID) or remote signing via ProID.
Installing and using the certificate
Once you have your certificate, you need to install it correctly in your operating system or certificate store:
Windows:
- Open the downloaded certificate file (.p12 or .pfx) by double-clicking it
- The import wizard will guide you through installing it in the Windows certificate store
- The certificate will then be available in applications that support electronic signatures (Adobe Acrobat, Microsoft Office, web browser)
macOS:
- Import the certificate file using the Keychain Access application
- Once imported, the certificate will be available in system applications
Linux:
- Installation depends on your distribution and the software you use
- Most applications use NSS or PKCS#11 storage
Don't forget to back it up!
After installing the certificate, create a backup of the private key file (.p12/.pfx) and store it somewhere safe (an encrypted USB drive, a safe). If you lose access to the certificate (computer replacement, disk failure), you'll need to apply for a new one — which costs both money and time.
Write down your certificate password and keep it somewhere secure. If you lose the password, the certificate cannot be recovered — you'll have to apply for a new one.
How much does an electronic signature cost — a full breakdown
Let's look at the real costs you can expect as an OSVČ.
Annual cost calculation for an electronic signature
Option A: Recognised electronic signature (most common for OSVČ)
| Item | One-time | Annual | |------|----------|--------| | Qualified certificate (PostSignum, 1 year) | – | 440 CZK | | Signing software | 0 CZK (free) | 0 CZK | | Total | 0 CZK | 440 CZK |
With a three-year certificate (990 CZK), the annual cost works out to 330 CZK.
Option B: Qualified electronic signature (QES)
| Item | One-time | Annual | |------|----------|--------| | Qualified certificate on smart card | – | from 500 CZK | | Smart card (qualified device) | from 500 CZK | – | | Smart card reader (if you don't have one) | from 300 CZK | – | | Total in year 1 | from 800 CZK | from 500 CZK | | Total in subsequent years | – | from 500 CZK |
Alternatives to having your own electronic signature
You don't always need your own certificate. In some cases, alternatives are available:
Banking identity (BankID)
Since 2021, you can use your banking identity to log in to online public administration services. BankID allows you to:
- Log in to the MOJE daně portal
- Log in to the ČSSZ ePortal
- Log in to your data mailbox
- Verify your identity for online PostSignum certificate issuance
However, BankID is not an electronic signature — it only serves for authentication (identity verification). It cannot be used for signing documents outside public administration portals.
eID Card (eObčanka)
A national ID card with an activated electronic chip (eObčanka) enables you to:
- Log in to online public administration services
- Create a qualified electronic signature (if a qualified certificate is stored on the chip)
To activate the electronic functions of your eID card, visit a municipality with extended powers — more information at portal.gov.cz.
Data mailbox
As mentioned above, submissions made through a data mailbox have the same legal effect by law as submissions signed with a recognised electronic signature. For most communication with authorities, a data mailbox alone will therefore suffice.
Remote signing — the modern approach
In recent years, remote (cloud) signing has become increasingly popular. The private key is not stored on your computer or smart card, but on the provider's secure server. You can sign from anywhere — from your phone, tablet, or any computer.
In the Czech Republic, remote qualified signing is offered by the ProID service from Software602, for example. You set up the certificate online, verify your identity via BankID or your eID card, and sign using a mobile app.
Advantages of remote signing:
- Sign from anywhere, on any device
- No smart card or card reader required
- The certificate is securely stored on the server
Disadvantages:
- Dependent on the provider's service availability
- Higher annual costs compared to a standard certificate
- Requires a mobile phone for authorisation
Practical uses of an electronic signature for OSVČ
Signing invoices
Electronic invoices (PDF) can be signed with an electronic signature. For standard invoices, this is not mandatory, but a signed invoice increases credibility — and for VAT payers, it makes it easier to demonstrate the authenticity of origin and integrity of the content of a tax document.
Signing contracts remotely
If you work with clients remotely, an electronic signature significantly speeds up the contract signing process. You prepare the contract as a PDF, sign it electronically, and send it by email. The other party then signs it in the same way.
Applications to the trade licensing office
Changes to your trade licence (adding activities, changing your registered address) can be made electronically through the Unified Registration Form using your electronic signature.
Communication with insurance providers and banks
An increasing number of institutions accept electronically signed documents. Health insurers, the ČSSZ, and some banks allow electronic submission of applications and notifications.
Common mistakes when working with an electronic signature
Things to watch out for
-
Expired certificate — Certificates have a limited validity period (1–3 years). Keep an eye on the expiry date and renew the certificate in time. A signature made with an expired certificate is not valid.
-
Mixing up signature types — For communication with public authorities, you need at least a recognised electronic signature (based on a qualified certificate). A simple signature is not sufficient.
-
Loss of the private key — Without a backup of the .p12/.pfx file and its password, you lose the ability to sign. The certification authority cannot restore your key.
-
Signing after revocation — If you suspect the certificate has been compromised (theft, loss of control), immediately revoke it with the certification authority. Signatures created after revocation are invalid.
-
Missing timestamp — For long-term archiving of signed documents, it is advisable to add a qualified timestamp, which proves that the signature was created while the certificate was still valid.
Frequently Asked Questions (FAQ)
Does an OSVČ have to have an electronic signature?
There is no direct legal obligation to own an electronic signature. The obligation to file electronically (tax returns, overviews) can also be met through a data mailbox, which OSVČ have set up automatically. However, an electronic signature is practically essential for signing documents outside the data mailbox environment.
What is the difference between a recognised and a qualified electronic signature?
A recognised electronic signature is an advanced electronic signature based on a qualified certificate — a certificate stored on your computer is sufficient. A qualified electronic signature (QES) additionally requires a qualified device (smart card, USB token), is equivalent to a handwritten signature, and is recognised across the entire EU.
How long is a qualified certificate valid?
The standard validity period for a qualified certificate is 1 year. PostSignum now also offers certificates valid for 3 years at a discounted price. Before the certificate expires, you must renew it or apply for a new one.
Can I use one certificate on multiple devices?
Yes. If your certificate is stored as a file (.p12/.pfx), you can install it on multiple devices. For certificates on a smart card, the signature is tied to the physical card — you can only sign on a device to which the card is connected.
What if I lose my certificate?
If you lose access to your certificate (disk failure, lost password), contact the certification authority and request revocation (invalidation) of the old certificate. Then apply for a new one — you will need to go through the entire issuance process again.
Are electronically signed contracts legally valid?
Yes. Under the eIDAS Regulation and Czech law, an electronic signature cannot be denied legal effect solely because it is in electronic form. A qualified electronic signature has the same legal effect as a handwritten signature. For lower-level signatures, it depends on the specific circumstances and the agreement between the parties.
Do I need an electronic signature to file through MOJE daně?
Not necessarily. You can also log in to the MOJE daně portal using your data mailbox or banking identity (BankID). An electronic signature is one of several options for logging in and signing submissions.
Summary: which electronic signature should an OSVČ get?
Recommendation for most OSVČ
For most Czech OSVČ, we recommend the following combination:
- Data mailbox (set up automatically since 2023) — for filing tax returns, overviews, and communicating with authorities
- Banking identity (BankID) — for logging in to public administration portals
- Qualified certificate from PostSignum (from 440 CZK/year) — for signing contracts, invoices, and other documents
This combination covers virtually all the everyday needs of an OSVČ at minimal cost. Only consider a qualified electronic signature (QES) on a smart card if you regularly sign documents with international partners or need a signature equivalent to a handwritten one.
DokladBot helps you keep track of your tax obligations, filing deadlines for overviews, and other tasks related to signing documents electronically. Just send a message via WhatsApp and ask anything about your business — try DokladBot at dokladbot.cz.
Useful links to official sources
- Czech Ministry of the Interior — list of qualified trust service providers — up-to-date list of certification authorities
- PostSignum — Czech Post certification authority — certificate requests, pricing, contact points
- I.CA — První certifikační autorita — qualified certificates and smart cards
- MOJE daně portal — electronic tax return filing
- ČSSZ ePortal — electronic submission of overviews
- Portal.gov.cz — eID card — information on the electronic features of the national ID card
This article is for informational purposes only and does not constitute legal advice. The information is based on legislation in force as of February 2026. For specific legal questions, we recommend consulting a legal professional. Always verify current terms and prices directly with the relevant certification authority.
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