BR-CO-17VAT category tax amount (BT-117) = VAT category taxable amount (BT-116) x (VAT category rate (BT-119) / 100), rounded to two decimals.

Why does BR-CO-17 happen?

Because the tolerance is a whole euro, a rounding drift of a few cents is precisely not the cause — that reports BR-CO-14 and BR-CO-15, which check exactly. BR-CO-17 fires when something larger went wrong: the wrong rate applied to the base, one category computed at another's rate, or a line that landed in the wrong category of the breakdown. At a rate of 0 a different branch of the expression applies: there it only requires the tax amount to round to zero. For exempt, intra-community and reverse-charge categories BR-CO-17 is therefore a zero check rather than a multiplication.

What the validator checks

The expression the official KoSIT rule set evaluates — not paraphrased, but read from the Schematron file it ships. UBL and CII address different document trees, so the same rule reads differently in each.

UBL

(round(cac:TaxCategory[cac:TaxScheme/normalize-space(upper-case(cbc:ID))='VAT']/xs:decimal(cbc:Percent)) = 0 and (round(xs:decimal(cbc:TaxAmount)) = 0)) or (round(cac:TaxCategory[cac:TaxScheme/normalize-space(upper-case(cbc:ID))='VAT']/xs:decimal(cbc:Percent)) != 0 and ((abs(xs:decimal(cbc:TaxAmount)) - 1 < round(abs(xs:decimal(cbc:TaxableAmount)) * (cac:TaxCategory[cac:TaxScheme/normalize-space(upper-case(cbc:ID))='VAT']/xs:decimal(cbc:Percent) div 100) * 10 * 10) div 100 ) and (abs(xs:decimal(cbc:TaxAmount)) + 1 > round(abs(xs:decimal(cbc:TaxableAmount)) * (cac:TaxCategory[cac:TaxScheme/normalize-space(upper-case(cbc:ID))='VAT']/xs:decimal(cbc:Percent) div 100) * 10 * 10) div 100 ))) or (not(exists(cac:TaxCategory[cac:TaxScheme/normalize-space(upper-case(cbc:ID))='VAT']/xs:decimal(cbc:Percent))) and (round(xs:decimal(cbc:TaxAmount)) = 0))

CII

(round(.[normalize-space(upper-case(ram:TypeCode)) = 'VAT']/xs:decimal(ram:RateApplicablePercent)) = 0 and (round(xs:decimal(ram:CalculatedAmount)) = 0)) or (round(.[normalize-space(upper-case(ram:TypeCode)) = 'VAT']/xs:decimal(ram:RateApplicablePercent)) != 0 and ((abs(xs:decimal(ram:CalculatedAmount)) - 1 <= round(abs(xs:decimal(ram:BasisAmount)) * (.[normalize-space(upper-case(ram:TypeCode)) = 'VAT']/xs:decimal(ram:RateApplicablePercent) div 100) * 10 * 10) div 100 ) and (abs(xs:decimal(ram:CalculatedAmount)) + 1 >= round(abs(xs:decimal(ram:BasisAmount)) * (.[normalize-space(upper-case(ram:TypeCode)) = 'VAT']/xs:decimal(ram:RateApplicablePercent) div 100) * 10 * 10) div 100 ))) or (not(exists(.[normalize-space(upper-case(ram:TypeCode))='VAT']/xs:decimal(ram:RateApplicablePercent))) and (round(xs:decimal(ram:CalculatedAmount)) = 0))

Source: rule set v2026-08-31

How do you fix BR-CO-17?

Group lines by VAT category, sum their net amounts into the taxable base BT-116, and compute the tax once from it: BT-116 × BT-119 / 100. Check the rate against the category first — at this magnitude it is almost always the rate that is wrong, not the rounding. For standard-rated categories BR-S-09 reports alongside this rule.

<cac:TaxSubtotal>
  <cbc:TaxableAmount currencyID="EUR">1000.00</cbc:TaxableAmount>
  <cbc:TaxAmount currencyID="EUR">70.00</cbc:TaxAmount>
  <cac:TaxCategory>
    <cbc:ID>S</cbc:ID>
    <cbc:Percent>19</cbc:Percent>
    <cac:TaxScheme><cbc:ID>VAT</cbc:ID></cac:TaxScheme>
  </cac:TaxCategory>
</cac:TaxSubtotal>

<cac:TaxSubtotal>
  <cbc:TaxableAmount currencyID="EUR">1000.00</cbc:TaxableAmount>
  <cbc:TaxAmount currencyID="EUR">190.00</cbc:TaxAmount>
  <cac:TaxCategory>
    <cbc:ID>S</cbc:ID>
    <cbc:Percent>19</cbc:Percent>
    <cac:TaxScheme><cbc:ID>VAT</cbc:ID></cac:TaxScheme>
  </cac:TaxCategory>
</cac:TaxSubtotal>