Overview
P_9A is the unit net price of one line item (in Polish, "cena jednostkowa netto"). It lives inside each FaWiersz block and is the price of a single unit of the item, before any VAT is added.
P_9A is required on every line. It is an amount field (TKwotowy in the XSD), so it accepts a decimal number with up to two decimal places and a dot as the decimal separator. A value such as 150.50 is valid; 150,50 is not, because the comma is not a decimal separator inside XML.
The unit net price is multiplied by the quantity (P_8B) to produce the line's net value (P_11). The result is rounded to two decimal places, and the VAT is then calculated from that net value using the rate in P_12. So P_9A is the starting point of every amount on the line: get it wrong, and the net value, the VAT and the total all shift with it.
Because P_9A is net, it must not already include VAT. A frequent integration bug is to copy the gross (VAT-inclusive) price from a catalogue into P_9A. If your SaaS plan sells for €199 including VAT, the unit net price is a different, lower number; compute it from the net amount before you send it.
In Notaly you send the unit net price as the unitNetPrice property of a line item, and Notaly writes it to P_9A. You never have to hand-format the XML number yourself. If unitNetPrice is missing or is not a number, the API rejects the payload with a 422 validation error before it reaches KSeF; values are written with two decimals.
A complete, valid FA(3) example appears below, with P_9A filled on both lines.
<Faktura xmlns="http://crd.gov.pl/wzor/2025/06/25/13775/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<Naglowek>
<KodFormularza kodSystemowy="FA (3)" wersjaSchemy="1-0E">FA</KodFormularza>
<WariantFormularza>3</WariantFormularza>
<DataWytworzeniaFa>2026-10-12T07:23:07Z</DataWytworzeniaFa>
<SystemInfo>einvoice-api</SystemInfo>
</Naglowek>
<Podmiot1>
<DaneIdentyfikacyjne><NIP>2745013933</NIP><Nazwa>Example Sp. z o.o. (FICTIONAL)</Nazwa></DaneIdentyfikacyjne>
<Adres><KodKraju>PL</KodKraju><AdresL1>ul. Testowa 1, 00-001 Warszawa</AdresL1></Adres>
</Podmiot1>
<Podmiot2>
<DaneIdentyfikacyjne><NIP>1234563218</NIP><Nazwa>Test Customer S.A. (FICTIONAL)</Nazwa></DaneIdentyfikacyjne>
<Adres><KodKraju>PL</KodKraju><AdresL1>ul. Probna 2, 30-001 Kraków</AdresL1></Adres>
<JST>2</JST>
<GV>2</GV>
</Podmiot2>
<Fa>
<KodWaluty>PLN</KodWaluty>
<P_1>2026-10-12</P_1>
<P_2>FV/2026/10/001</P_2>
<P_13_1>1000.00</P_13_1><P_14_1>230.00</P_14_1>
<P_13_2>301.00</P_13_2><P_14_2>24.08</P_14_2>
<P_15>1555.08</P_15>
<Adnotacje>
<P_16>2</P_16><P_17>2</P_17><P_18>2</P_18><P_18A>2</P_18A>
<Zwolnienie><P_19N>1</P_19N></Zwolnienie>
<NoweSrodkiTransportu><P_22N>1</P_22N></NoweSrodkiTransportu>
<P_23>2</P_23>
<PMarzy><P_PMarzyN>1</P_PMarzyN></PMarzy>
</Adnotacje>
<RodzajFaktury>VAT</RodzajFaktury>
<FaWiersz>
<NrWierszaFa>1</NrWierszaFa>
<P_7>SaaS subscription - October</P_7>
<P_8A>pcs.</P_8A>
<P_8B>1</P_8B>
<P_9A>1000.00</P_9A>
<P_11>1000.00</P_11>
<P_12>23</P_12>
</FaWiersz>
<FaWiersz>
<NrWierszaFa>2</NrWierszaFa>
<P_7>Support</P_7>
<P_8A>hrs.</P_8A>
<P_8B>2</P_8B>
<P_9A>150.50</P_9A>
<P_11>301.00</P_11>
<P_12>8</P_12>
</FaWiersz>
</Fa>
</Faktura>Sources
Source: crd.gov.pl