bcquality/microsoft/knowledge/data-modeling/document-line-prices-follow-prices-including-vat.md
Kilian Seizinger a2685b9c86
knowledge(data-modeling): Prices Including VAT decides the basis of sales/purchase/service line amounts (#203)
* Frist draft for Prices Incl. VAT Data Modelling

* knowledge(data-modeling): cover prepayment, service line and ExclTax helper in Prices Including VAT article

Extend the community article on sales/purchase line prices following the
header's Prices Including VAT:

- Group the line fields: fields that follow the header flag (Unit Price,
  Direct Unit Cost, Line Amount, discounts, Prepmt. Line Amount,
  Prepmt. Amt. Inv., Prepmt Amt to Deduct, Prepmt Amt Deducted) versus
  fields with a fixed basis (Amount, VAT Base Amount, Prepayment Amount
  are net; Amount Including VAT, Prepmt. Amt. Incl. VAT,
  Prepmt. Amount Inv. Incl. VAT are gross).
- Add the rule to combine only fields of the same group, with BaseApp's
  UpdatePrepmtAmounts as the correct example.
- Add the misleading-name case: CalculateOutstandingAmountExclTax on
  Sales Line and Purchase Line is based on Line Amount and includes VAT
  on a Prices Including VAT document. BaseApp pairs it only with
  Prepmt. Line Amount (same basis); extension code that treats it as net
  is wrong.
- Mention that Service Line uses the same caption switch and
  UpdateVATAmounts split for Unit Price and Line Amount.
- Samples: add GetOutstandingNetAmount (bad: trusts the helper's name;
  good: takes the uninvoiced share of Amount).
- al-data-modeling-review: widen the scope and the worklist rule to
  service lines, the extra prepayment fields and
  CalculateOutstandingAmountExclTax, and exclude code that only combines
  fields of the same group.

Verified against BCApps W1 BaseApp (SalesLine, PurchaseLine, ServiceLine,
SalesHeader, Sales Line CaptionClass Mgmt).

Refs #151

* knowledge(data-modeling): move Prices Including VAT article to Microsoft layer

data-modeling is a Microsoft-owned review domain consumed by
microsoft/skills/review/al-data-modeling-review.md, and
docs/contributing.md does not allow Community as a staging layer for
such domains. Move the article and its .good.al/.bad.al samples to
microsoft/knowledge/data-modeling/. Content is unchanged; the slug-based
evaluation entry stays as is.
2026-10-02 09:51:34 +02:00

5.8 KiB

bc-version domain keywords technologies countries application-area
all
data-modeling
prices-including-vat
unit-price
line-amount
direct-unit-cost
prepmt-line-amount
amount-including-vat
sales-line
purchase-line
service-line
net-gross
al
w1
all

Sales, purchase, and service line prices follow the header's Prices Including VAT

Contributions welcome — open a PR to refine or extend this article.

Description

Line prices are gross or net depending on the header's Prices Including VAT. When the flag is set, Unit Price (sales, service), Direct Unit Cost (purchase), Line Amount, Line Discount Amount, Inv. Discount Amount, and the prepayment fields Prepmt. Line Amount, Prepmt. Amt. Inv., Prepmt Amt to Deduct, and Prepmt Amt Deducted all include VAT. When it is cleared they exclude it. Only Amount, VAT Base Amount, and Prepayment Amount (always net) and Amount Including VAT, Prepmt. Amt. Incl. VAT, and Prepmt. Amount Inv. Incl. VAT (always gross) keep a fixed basis. Code that mixes the two groups without looking at the header flag is wrong for every document whose customer or vendor uses the other setting.

Best Practice

When code needs a known basis — exports, integrations, KPIs, custom totals, commission or margin calculations — read Amount for net and Amount Including VAT for gross. Both are already reduced by line and invoice discounts and are maintained by the line's VAT calculation, so no VAT arithmetic is needed.

When code combines fields, pair fields of the same group. BaseApp's UpdatePrepmtAmounts sets Prepmt. Line Amount from Line Amount minus Inv. Discount Amount. This is correct because all three follow the header flag. Prepmt. Amt. Inv. pairs with Prepmt. Line Amount; Prepmt. Amount Inv. Incl. VAT pairs only with other gross values.

When code writes a price from an external source whose basis is known (an EDI price list, an API payload, a web-shop order), get the document header and convert the source price into the header's basis before validating Unit Price or Direct Unit Cost, using the line's VAT % and the currency's Unit-Amount Rounding Precision. Alternatively, set Prices Including VAT on the header to match the source before the first line is created. Toggling it later on a sales header with priced lines asks the user to confirm a recalculation. Without a UI session, or when validation dialogs are hidden, BaseApp converts all line prices without asking.

The standard price calculation already converts a Price List Line whose Price Includes VAT differs from the document's setting, so a price it returns is in the document's basis and must not be converted a second time.

On purchase lines, Unit Cost and Unit Cost (LCY) are derived from Direct Unit Cost with VAT removed, so they stay net. Service lines follow the same rule for Unit Price and Line Amount: they share the caption switch and the UpdateVATAmounts split of the sales line.

See sample: document-line-prices-follow-prices-including-vat.good.al.

Anti Pattern

Treating Unit Price, Direct Unit Cost, or Line Amount as net by default. Typical signals: summing Line Amount as a document's net total, computing VAT as Line Amount * "VAT %" / 100, putting a known net or gross external price straight into Unit Price or Direct Unit Cost, or comparing a line price with Item."Unit Price" or Item."Last Direct Cost" — all without reading the header's Prices Including VAT. For a gross-price customer at 19 % VAT, a net total built from Line Amount is 19 % too high, and a net price of 100 imported unconverted yields a net revenue of only 84.03.

Trusting a name instead of the source fields. The public procedure CalculateOutstandingAmountExclTax on Sales Line and Purchase Line returns Line Amount minus Inv. Discount Amount for the uninvoiced quantity, so its result includes VAT on a Prices Including VAT document despite its name. BaseApp only combines it with Prepmt. Line Amount, which has the same basis. Extension code that uses it as a net outstanding amount — compared with Amount, exported as net, or used to compute VAT — has this defect. The same applies to any variable or procedure named ExclVAT, ExclTax, or Net that is fed from a header-dependent field.

Do not report code that reads the header flag, uses only fixed-basis fields, or only combines fields of the same group (for example, prepayment amounts derived from Line Amount, or values copied between two lines of the same document).

See sample: document-line-prices-follow-prices-including-vat.bad.al.

References