FAQ

Find answers to 12 frequently asked questions about SUBMIT DE, organized by topic.

General (12)

What is the BSI certificate number of my TSS?

There are two ways to obtain the valid BSI certificate number of a TSS:

**1. In the fiskaly Dashboard **

• Navigate to: Germany > SIGN DE V2 > Technical Security System.

• In the table overview, you will see the BSI certificate number for each TSS.

• On the detail page of the particular TSS, the certificate number is also displayed.  

 

**2. Via fiskaly SIGN DE (ListTss or RetrieveTss endpoint)  **

• Call the listTss endpoint / retrieveTss endpoint.

• The BSI certificate number can be found in the response field data[].bsi_certification_id.

How to get the fiskaly data for the POS registration in Germany

Are you a taxpayer and required to register your POS system with the German tax authority (Finanzamt) yourself? This article explains how to access the BSI certificate ID and the serial number of the Technical Security Device (TSS) via the fiskaly system.

Other information such as the software version, model, or serial number of your POS system must be obtained directly from your POS provider or the provider of your POS software.

BSI Certificate ID

You can find the current BSI certificate ID of the fiskaly TSS in our article: Which BSI certificate ID should be used for a fiskaly TSS?

TSS Serial Number

The TSS serial number can be found on a receipt from your POS system:

• either in the QR code, which you can scan using our free fiskalcheck app - Google Play Store (Android) / Apple App Store (iOS)

• or directly in plain text on the receipt if provided (part of the TSS signature)

Details about the fields contained in the TSS signature can be found in this article: Which data should be recorded on a receipt?

How Can I Test Submission Statuses in the Submission API?

Some submission statuses may occur in the live environment but cannot be deliberately triggered within our infrastructure. The following statuses are affected:

XML_GENERATION_FAILED: This status should not normally occur, as only data that passes all validations and business rules proceeds to XML generation.

TRANSMISSION_FAILED: This cannot be triggered manually, as it results from communication errors with ELSTER.

ERROR: Refers to rare internal system errors that cannot be deliberately tested.

INTERNAL_VALIDATION_FAILED: Occurs when users submit invalid data.

Testing Error States

To simulate these or other errors, we recommend implementing a mock proxy on your side that returns predefined responses. This gives you full control over your test scenarios.

Test Scenario for EXTERNAL_VALIDATION_FAILED

This status occurs when a submission is rejected by ELSTER. You can deliberately trigger it by setting the clientType to 4 (taximeter) or 5 (odometer) in the UpsertClientAdditionalData endpoint and leaving the remarks field empty. In this case, ELSTER will reject the submission.

Simulating Delays

We do not support simulating delays (e.g., VALIDATION_TRIGGERED, TRANSMISSION_IN_PROGRESS) within our environment. Mocking the behavior on your side is the most effective solution.

How to register a POS that was connected to a TSS that can no longer be used?

If a TSS originally assigned to a cash register (POS system) becomes defective and can no longer be used, you need to register a new TSS. To ensure compliance and avoid duplicate entries, follow these steps when using the Submission API.

Scenario

You want to continue using a POS system, but its previously assigned TSS is no longer functional. In this case:

• A new Client (with a new client_id) must be created.

• The same serial_number should be used, since the hardware (the POS system) has not changed.

• The old Client connected to the defective TSS must be removed from the

• Submission/Transmission to avoid duplicate entries.

Recommended Procedure

1. Create a new TSS

Use the SIGN DE API to create a new TSS which replaces the defective one.

2. Create a new Client

Create a new Client with a new client_id. Use the same serial_number as specified previously – this represents the unchanged POS serial number.

3. Remove the old Client via the Submission API

Use the DELETE endpoint in the Submission API to remove the old Client from the Submission/Transmission (DeleteClientAdditionalData). This step is crucial to ensure that the Submission/Transmission does not include two Clients with the same serial_number.

See also: What are the important steps for reporting the decommissioning of a client connected to a fiskaly TSS?

Create a new Submission/Transmission

Once the new Client and TSS are registered, and the old Client has been removed from the Submission, create a new Submission message to complete the process.

Note

It is not necessary to deregister the POS system itself. The cash register is still in use – only the TSS has been replaced. By assigning the same serial_number to the new Client, you ensure a consistent and valid Submission structure.

What are the important steps for reporting the decommissioning of a client connected to a fiskaly TSS?

In order to decommission a Client (POS device) please follow the following steps:

1. Update client information

If the Client is no longer in use, you must update its status using the Submission API:

• Use the Upsert Client Additional Data endpoint

• Update the following fields:

date_decommissioning: The date the device was decommissioned

decommissioning_reason: A short description or keyword explaining the reason

Common reasons include:

• Sale

• Disposal (e.g. recycling or destruction)

• Theft

• Defect or technical failure

• Relocation to another establishment

Important: Do not delete the Client immediately. First, update the decommissioning fields and report the changes accordingly.

2. Report the changes to the tax authorities

Within 30 days, submit the updated information by creating a new Submission/Transmission via the Submission API.

3. Remove or unlink the client

Once the Submission/Transmission has been completed successfully, you can either:

• Delete the Client from your system, or

• Unlink the Client from the associated establishment if it will be reused elsewhere.

Summary

• Update Client data using date_decommissioning and decommissioning_reason

• Create a Submission/Transmission within 30 days

• Delete or unlink the Client after successful Submission/Transmission

For full API details, visit our Submission API documentation.

What if I only have a shorter tax number?

Depending on its format and source, the tax number may appear shorter than 13 digits. However, certain digital processes – such as registering a POS system with the tax office – require the standardized 13-digit format.The official tax number converter of the BMF can be used to generate the current 13-digit format from an older tax number. You simply need to select the federal state and enter the existing number.

Tax number ≠ Tax ID

Important: The 13-digit tax number is not the same as the tax identification number (Tax ID). The Tax ID is personal, consists of 11 digits, and remains the same for life. The tax number, on the other hand, can change over time – for example, due to moving, getting married, or changing tax offices.

Where can I find the 13-digit tax number?

The tax number can be found in various official documents, such as:

Income tax assessment notice

Wage tax statement or payslip

Exemption order for capital gains (issued by your bank)

If the number cannot be found, please reach out to the respective tax office.

 

💡 In the fiskaly SIGN DE x Submission API, the tax number corresponds to the field tax_number.

 

With the BMF’s tax number converter, a state-specific tax number can easily be converted into the standardized 13-digit ELSTER tax number.

What is the 13-digit tax number?

The 13-digit tax number plays a central role in the tax identification of businesses and self-employed individuals in Germany. It is issued by the respective tax office and is used to clearly assign all tax-related matters – from income tax to VAT.

Structure of the tax numberSince the introduction of the ELSTER system, the tax number consists of 13 characters. It is made up of several components:

Tax office number (2–3 digits): The final digits of the code assigned to the responsible tax office

District number (3–4 digits): Length varies depending on the federal state

Identification number (3–4 digits): A unique sequence to distinguish between taxpayers

Control digit (1 digit): Used to detect errors

❗ Note: The exact structure can vary by the federal state. In North Rhine-Westphalia, for example, the district number consists of 4 digits and the identification number of 3 digits – in other states, it’s the other way around.

With the BMF’s tax number converter, a state-specific tax number can easily be converted into the standardized 13-digit ELSTER tax number.

Which BSI certificate ID should be used for a fiskaly TSS?

The current fiskaly SIGN DE v2 TSS BSI certificate ID is 0717-2025.

The following article describes how to find the BSI certificate number:

Which BSI certificate number does my TSS have?

Where can I find the TSS serial number?

The TSS serial number can be found either via the fiskaly Dashboard in the TSS detail view (“Certificate Serial No.”), or in the response of the SIGN DE V2 endpoint retrieveTss (serial_number).

Additionally, the TSS serial number is shown if you use our fiskalcheck App to scan the QR code of a receipt.

For all further data required in order to fulfill the declaration requirement (Mitteilungspflicht) please reach out to your POS provider.

When will the reporting obligation for electronic recording systems come into effect?

From January 1, 2025, all electronic recording systems must be reported to the tax office. The reporting obligation applies to cash registers (PoS systems) as well as EU taximeters and odometers.

In order to ensure compliance with these legal requirements, the fiskaly SIGN DE x Submission API enables fast and efficient reporting of cash registers to the tax office.

Important deadlines:

Systems acquired before July 1, 2025 must be reported by July 31, 2025.

Systems acquired from July 1, 2025 must be reported within one month of acquisition (purchase).

Systems decommissioned from July 1, 2025 must be reported within one month of decommissioning.

Before reporting the decommissioning of a system, its acquisition must have already been reported. Systems that were permanently decommissioned before July 1, 2025, and are no longer in operation, only need to be reported if their acquisition was previously reported.

For EU taximeters and odometers, there are specific regulations. Details can be found in our blog.

Which value should I use as BSI ID?

When adding an external TSS to your Establishment via the endpoint Create or update an external TSS, you need to use the required field bsi_id.

The BSI ID corresponds to the ID of the certificate issued by the German Federal Office for Information Security (BSI - Bundesamt für Sicherheit in der Informationstechnik).

The certificate ID of a fiskaly TSS (as well as the ID of other certified Technical Security Systems) is published on the official page of the German Federal Office for Information Security. 

 

Example:

Name: fiskaly sign Cloud-TSE

Certificate ID: BSI-K-TR-0717-2025

In this case, the correct value for the field bsi_id would be 0717-2025.