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Software for validity check of exemption certificate

Project duration: 8 months

Brief description

In the future, construction customers must check whether a construction supplier still has a valid exemption certificate for construction withholding tax (FSB). If the customer transfers the construction work to the supplier despite an invalid FSB and does not retain the deduction of 15% of the construction withholding tax, he may be penalized. To check the FSB, the Federal Central Tax Office (BZSt) offers a mass query option via XML-RPC interface. The customer had decided to use a third-party solution here. An implementation of the call of the XML-RPC interface in SAP was ruled out. In the search for a third-party provider, the FSB Shake software from the company Vembex was identified as a possible solution. By preparing the relevant data from the SAP ERP system, the necessary data can be assigned to FSB Shake in the form of a CSV file. The necessary information about an FSB can then be determined here. Thus a statement can be made as to whether an FSB is valid.


The construction withholding tax is a form of taxation intended to curb illegal employment in the construction industry. Since 01.01.2002, entrepreneurial clients of construction services are obliged to withhold 15% of the invoice amount and pay it to the tax office. With the date 19.07.2022 there is a revision of the BMF letter of 27.12.2002 with the subject: Tax deduction of remuneration for construction services rendered in Germany (paragraphs 48 to 48d EStG); revision of the BMF letter of 27 December 2002 (BStBl I page 1399). In the event of an invalid FSB, further information can then be obtained or payment for the construction work can be suspended for the time being. The customer was supported in the selection of software. The FSB Shake was then introduced, with extensive testing.

Subject description

The result of the FSB check means that construction suppliers without a valid FSB are excluded during the payment run. The department contacts the supplier or asks the tax office whether an FSB has not been transmitted to the BZSt. This case also occurred during the test runs.


Project period04.09.2022 - 09.05.2023

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