[Event Request] Codeunit 90 "Purch.-Post"- OnBeforePostWHT

[matilda-teitzel]

Why do you need this change?

Hi Microsoft AL Development Team,

Could you please add an OnBeforePostWHT IsHandled integration event to the PostWHT procedure in codeunit 90 "Purch.-Post"?

We have a use case where a particular region requires a custom WHT Gross Up Calculation Method, which isn't supported by standard. This integration event would allow us to achieve this custom Withholding Tax calculation, while ensuring the related ledger entries are aligned. This is currently preventing them from posting and finalising Purchase Invoices.

We believe the WHT features are region specific to the AU-version of Business Central, so these objects and procedures are lacking integration events for us to modify this process. The current alternative would be to utilise the OnBeforePostInvoice integration event, which we would like to avoid handling so we don't override or impact other Purchase Posting Events.

Please let me know if you have any questions.

Thank you.

Kind regards,
Matilda Teitzel

Describe the request

Hi Microsoft AL Development Team,

Could you please the following integration event to the PostWHT procedure in codeunit 90 "Purch.-Post"?

[IntegrationEvent(false, false)]
    local procedure OnBeforePostWHT(var PurchHeader: Record "Purchase Header"; var TotalInvAmount: Decimal; var PurchInvHeader: Record "Purch. Inv. Header"; var PurchCrMemoHeader: Record "Purch. Cr. Memo Hdr."; var TempPurchLineGlobal: Record "Purchase Line" temporary; var WHTEntry: Record "WHT Entry"; var IsHandled: Boolean)
    begin
    end;

Currently, the closest integration event is OnBeforePostInvoice, which we would like to avoid handling so we don't override or impact other Purchase Posting Events.

We did investigate Codeunit 28040 WHTManagement, however this doesn't have any integration events to leverage. I believe this feature is specific to the AU-region version of Business Central.

Please let me know if you have any questions.

Thank you.

Kind regards,
Matilda Teitzel
Internal work item: AB#618278

[AleksandricMarko]

Hi @matilda-teitzel,

Thanks for submitting this extensibility request. To help us process it efficiently, please update the issue to include the required information.

📚 Extensibility Guidelines

Missing Information:

• Alternatives Evaluated: While you mention OnBeforePostInvoice and Codeunit 28040 WHTManagement, please explain in detail WHY these alternatives are insufficient or what specifically you tried with them.

• Justification for IsHandled: Please provide specific justification for why IsHandled bypass functionality is necessary instead of a regular event. Explain why a standard event, redesign, or contribution isn't feasible with specific technical reasons.

• Performance Considerations: Please provide information about expected execution frequency and potential performance impact of this event.

• Data Sensitivity Review: Please confirm whether this event could expose sensitive data and address any security considerations.

• Multi-Extension Interaction: Please discuss the risks if multiple extensions subscribe to this IsHandled event and describe your conflict mitigation strategies.

Please update the issue with the missing details. We'll automatically re-analyze once updated.

[matilda-teitzel]

Hi @AleksandricMarko , thanks for reviewing! I have included further information below:

Alternatives Evaluated:
As mentioned, We did investigate Codeunit 28040 WHTManagement, however this doesn't have any integration events to leverage.
We did look into proposing adding standard Event Subscribers here, however this would not be as effective since the Gross Up Method would require intervening in multiple procedures which could introduce complexities with maintaining G/L Entry consistency between Vendor, Journal and WHT Entry impacts.

With the alternative OnBeforePostInvoice, the concern here is that we would need to Handle this, which would bypass integration events for other extensions, so is not ideal. This would also require re-implementing the Post Invoice logic, which would not have system stability long-term.

Part of our requirements are managed through existing Event Subscribers in the Purch Post Codeunit, however the lack of Integration Events surrounding WHT is causing consistency errors preventing Purchase Invoice posting. So we need additional support to handle the WHT Calculations and Applied Entries, so that this is consistent with Purchase Invoice Posting handling.

Justification for IsHandled:
IsHandled is required over a standard integration event, as this custom WHT Gross Up Calculation needs to bypass the standard WHTManagement functions to refer to custom WHTManagement procedures to update the Amount and Base management of the WHT Entry, WHT Gen Journal, and related Vendor Ledger Entries to be consistent with the Purchase Invoice Posting.
Additionally, the standard WHT behaviour doesn't include the TotalInvAmount variable context, which is required in an extension for these WHT Gross Up calculations.

We have already investigated the potential of a redesign from our end, and this is not feasible due to insufficient events in the WHT module and lack of events in the Purch Post Codeunit which access WHT Entry fields or call on WHTManagement. These WHTManagement processes were successfully modified in a previous version in NAV, so this has been a limitation with transitioning to the latest version of Business Central.

This is a specific regional requirement to override WHT Calculations to support a Gross Up calculations, which would not be feasible as a contribution, as it is a unique use case. Gross-Up methods are also not available in other functional areas on Business Central, so would not make sense to contribute this specifically to WHT, without applying to other areas.

Performance Considerations:
This will only be utilised for Posting specific Purchase Invoices, with WHT Enabled on the General Ledger Setup and a custom Gross Up WHT Calculation field selected. We are expecting minimal performance impact, as the functionality will just modify the Amount/Base Totals on the WHTEntry and related Journal / Vendor Ledger Entries and update the Gross Up Method field.

Data Sensitivity Review:
This event doesn't introduce any unique security concerns, as no sensitive data is included, and the variables are similarly exposed during Post Purch Invoice.

Multi-Extension Interaction:
Conflicts will be mitigated by only using IsHandled when specific conditions are met on a Purchase Document, otherwise standard PostWHT behaviour will be conducted. Since WHT is a regional feature, this would also only be applicable to a subset of Business Central uses.

Let me know if you have any further questions and I'd be happy to provide further details.

[AleksandricMarko]

✅ Analysis complete - approved for implementation

---

Implementation:

Add an integration event OnBeforePostWHT at the beginning of the PostWHT procedure in Codeunit 90 "Purch.-Post" to allow subscribers to override the default WHT posting behavior.

Location in PostWHT procedure (line 7896):

local procedure PostWHT(var PurchHeader: Record "Purchase Header"; TotalInvAmount: Decimal)
var
    GenJnlLine: Record "Gen. Journal Line";
    WHTPostingSetup: Record "WHT Posting Setup";
    GLReg: Record "G/L Register";
    InvoiceWHTEntryExists: Boolean;
    IsHandled: Boolean;  // <-- Add this variable
begin
    OnBeforePostWHT(PurchHeader, TotalInvAmount, PurchInvHeader, PurchCrMemoHeader, TempPurchLineGlobal, WHTEntry, IsHandled);  // <-- New event call
    if IsHandled then
        exit;

    if TempPurchLineGlobal.Type <> TempPurchLineGlobal.Type::" " then
        WHTPostingSetup.Get(TempPurchLineGlobal."WHT Business Posting Group", TempPurchLineGlobal."WHT Product Posting Group");
    if PurchHeader."Document Type" in [PurchHeader."Document Type"::Order, PurchHeader."Document Type"::Invoice] then begin

Event Publisher (add at the end of the codeunit with other events):

[IntegrationEvent(false, false)]
local procedure OnBeforePostWHT(var PurchHeader: Record "Purchase Header"; var TotalInvAmount: Decimal; var PurchInvHeader: Record "Purch. Inv. Header"; var PurchCrMemoHeader: Record "Purch. Cr. Memo Hdr."; var TempPurchLineGlobal: Record "Purchase Line" temporary; var WHTEntry: Record "WHT Entry"; var IsHandled: Boolean)
begin
end;

---

File: PurchPost.Codeunit.al

[JesperSchulz]

Thanks for reporting this. We agree, and we’ll publish a fix asap, either in an update for the current version or in the next major release. Please do not reply to this, as we do not monitor closed issues. If you have follow-up questions or requests, please create a new issue where you reference this one.

Build ID: 44688.