BT-117

How should VAT in BT-117 be calculated on a summary invoice?

Short answer

BT-117 is the VAT amount for the relevant tax category in the tax breakdown. On a summary invoice, the calculation must comply with EN 16931, Peppol BIS and the VAT Act. If VAT calculated historically for separate supplies differs from a calculation based on the combined taxable amount, the document structure and rounding must be designed to pass business validation without distorting the tax.

BT-117

Amount of VAT

Tax for a specific category in summary.

Summary invoice

More deliveries

May create rounding differences.

Validation

Mathematics of the document

Checks relationships between rows and summary.

ERP

Consistent rules

The calculation must be explainable and repeatable.

Detailed explanation

A summary invoice may cover multiple deliveries over a specific period. A problem arises with differences of a few cents: if tax is calculated separately for each delivery and then totalled, the result may not match the calculation based on the summary total. However, in a structured e-invoice, the links between lines, tax bases, tax categories and the total are also checked. It is therefore necessary to configure the ERP system to use consistent rounding, or to split supplies into separate tax categories or documents if the business case requires it.

As set out in the law and technical rules

The VAT Act regulates the incurrence of tax liability, the tax base and invoicing. EN 16931 and Peppol BIS check whether the summary tax data is mathematically consistent with the invoice structure.

Practical examples

Three separate supplies have VAT rounded to the nearest cent; the ERP system must determine how to correctly reflect this in the summary invoice.
Where VAT rates are combined, each category has its own tax total.
If there is a difference of one cent, the calculation or structure must be corrected; do not manually rewrite the BT-117 without linking it to the lines.

Common misconceptions

“I can manually adjust the BT-117 to make the result match.” Not without linking it to the lines and the calculation rules.
“The validator does not handle differences of one cent.” It handles them via rounding rules and tolerances.
“A summary invoice eliminates the need for correct line items.” No. Line items and totals must be consistent.

Conclusion

BT-117 must reconcile with the tax breakdown and calculation rules; resolve rounding differences systematically rather than manually changing one isolated field.

Legal and technical basis

Act No. 222/2004 Coll. on VAT, Section 22
Act No. 222/2004 Coll. on VAT, Section 74
EN 16931
Peppol BIS Billing 3.0 – Tax total and VAT breakdown rules

Official cases from the Slovak Financial Administration’s FAQs

The following questions and answers are taken from the current July FAQ from the Financial Administration and have been assigned to this topic. Grouping the cases prevents the creation of duplicate pages, whilst retaining the full answer and the exact wording of the question.

Example No. 41: Summary invoice and VAT calculation (BT-117): For summary invoices, VAT is calculated on the individual tax bases for separate supplies listed in the summary invoice. It follows that the tax result on BT-117 may not correspond to the EN standard, which calculates VAT on the total tax base. How should the BT-117 field be completed in the case of summary invoices covering several separate supplies, for which separate tax bases and the corresponding VAT on those tax bases have been calculated?

There has been a change in the rules governing summary invoices. Whilst it will still be possible until 31 December 2026 to issue a summary invoice for repeated supplies of goods or services over several periods (several months), from 1 January 2027 it will only be possible to issue a summary invoice for repeated supplies made within a single month. This will certainly lead to a decline in the use of summary invoices. However, this does not alter the fact that the standard specifies BT-117 ‘Total tax amount per category’, which forms part of the BT BG-23 ‘VAT breakdown’ group, as a mandatory component of the e-invoice (cardinality 1..1). Calculation of BT-117: BT-116 (total amount of tax bases for the VAT category) × BT-119 (VAT category code). Calculation of BT-116: the sum of (all tax bases for a specific tax category (BT-131) + surcharges at invoice level – deductions at document level). The calculation of BT-131 is the net amount on the invoice line – tax bases. Example: Summary invoice (Pro forma) Document number: 202604001 Period: 01/04/2026 – 30/04/2026 Delivery date Description of goods Quantity Unit price (excl. VAT) Tax base (BT-131) VAT (23%) Total price (incl. VAT) 05/04/2026 Goods XYZ (Steel) 10 t €600.00 €6,000.00 €1,380.00 €7,380.00 12/04/2026 Goods XYZ (Steel) 8 t €600.00 €4,800.00 €1,104.00 €5,904.00 19 April 2026 Goods XYZ (Steel) 12 t €610.00 €7,320.00 €1,683.60 €9,003.60 26 April 2026 Goods XYZ (Steel) 10 t €610.00 €6,100.00 €1,403.00 €7,503.00 TOTAL 40 t €24,220.00 €5,570.60 €29,790.60 ________________________________________ Summary • Total taxable amount: €24,220.00 (BT-116) • VAT rate (23%) – total: €5,570.60 (BT-117) • Amount payable: €29,790.60 (BT-115)

Primary source: Financial Administration of the Slovak Republic, FAQ 9/VAT/2025/IM k e-invoice, July 2026 update. Processed and checked on 13 July 2026.