4B Software - HowTo - Microsoft Dynamics 365

VAT Adjustment for Payment Discounts in Microsoft Dynamics NAV / Business Central

Tue, 25 Aug 2026 11:00:00 +0000

When using payment discounts, it is important to configure correctly how VAT should be handled when the discount is applied.

For this purpose, the system provides the Adjust for Payment Discount setting in the VAT Posting Setup.

This setting determines whether the system should also adjust the VAT amount originally posted on the invoice when a payment discount is applied.

1. What is a payment discount?

A payment discount is a discount granted to a customer or vendor if an invoice is paid within a specified period.

Example:

Invoice base amount: 1,000.00 EUR
VAT 23%: 230.00 EUR
Invoice total: 1,230.00 EUR
Payment discount: 2%

If the customer meets the payment discount conditions, they will pay:

1,230.00 × 98% = 1,205.40 EUR

The difference represents a payment discount of:

24.60 EUR

2. Where is the VAT adjustment configured?

The setting is available in:

VAT Posting Setup

For the relevant combination of:

VAT Business Posting Group
VAT Product Posting Group

the following field is available:

Adjust for Payment Discount

This means that the setting can be configured separately for individual VAT posting group combinations.

For the system to adjust VAT for payment discounts, the corresponding functionality must also be enabled in General Ledger Setup. The functionality is enabled globally and then configured for specific combinations in VAT Posting Setup.

3. Adjust for Payment Discount is enabled

If Adjust for Payment Discount is enabled, the system also adjusts the VAT amount when the payment discount is applied.

Let us use the following example:

Parameter	Value
Invoice base amount	1,000.00 EUR
VAT	23%
VAT on invoice	230.00 EUR
Invoice total	1,230.00 EUR
Payment discount	2%

The payment discount amount is:

1,230.00 × 2% = 24.60 EUR

The system splits the payment discount between the VAT base and the VAT amount.

Item	Original amount	Adjustment	Amount after discount
VAT base	1,000.00 EUR	-20.00 EUR	980.00 EUR
VAT 23%	230.00 EUR	-4.60 EUR	225.40 EUR
Total	1,230.00 EUR	-24.60 EUR	1,205.40 EUR

After applying the payment discount, the resulting VAT base is:

980.00 EUR

and the resulting VAT amount is:

225.40 EUR

Calculation check:

980.00 × 23% = 225.40 EUR

When the invoice is paid, the system therefore adjusts the originally posted VAT by 4.60 EUR.

4. How is the transaction posted?

When the invoice is issued, the following amounts are initially posted:

Account	Amount
Customer receivable	1,230.00 EUR
Revenue	1,000.00 EUR
VAT	230.00 EUR

If the customer pays the invoice within the payment discount period, they pay:

1,205.40 EUR

The difference of 24.60 EUR represents the payment discount.

If VAT adjustment is enabled, this difference is split into:

20.00 EUR – payment discount related to the VAT base
4.60 EUR – VAT adjustment

The resulting VAT amount for the transaction is therefore reduced from:

230.00 EUR

to:

225.40 EUR

The system performs this adjustment when the invoice is applied against the payment, provided that the payment discount conditions are met.

5. What happens if Adjust for Payment Discount is disabled?

If Adjust for Payment Discount is disabled, the system does not adjust VAT when the payment discount is applied.

Using the same example, the customer still pays:

1,205.40 EUR

but the original VAT amount remains:

230.00 EUR

The system therefore does not create a VAT adjustment of 4.60 EUR.

The difference between the original invoice amount and the payment received is posted as a payment discount according to the configured posting accounts.

6. Comparison of both options

Setting	Adjustment enabled	Adjustment disabled
Original invoice	1,230.00 EUR	1,230.00 EUR
Customer payment	1,205.40 EUR	1,205.40 EUR
Payment discount	24.60 EUR	24.60 EUR
Original VAT	230.00 EUR	230.00 EUR
VAT adjustment	-4.60 EUR	0.00 EUR
Final VAT	225.40 EUR	230.00 EUR

The difference is therefore not in the amount paid by the customer, but in whether part of the payment discount is also reflected in VAT.

7. Important configuration

It is not sufficient to check only the Adjust for Payment Discount field on a specific line in VAT Posting Setup.

The functionality must also be enabled in General Ledger Setup.

You can then define which VAT posting group combinations should use this adjustment.

If a company uses several VAT rates, the setting should therefore be checked separately for each relevant posting group combination.

8. When does the system perform the VAT adjustment?

The setting itself does not mean that VAT will be adjusted on every invoice.

The VAT adjustment is performed when:

the invoice uses payment terms that include a payment discount,
the customer or vendor meets the conditions for receiving the discount,
the payment is applied to the relevant invoice,
payment discount VAT adjustment is enabled,
the relevant VAT posting group combination has Adjust for Payment Discount enabled.

The VAT adjustment is therefore created only when the payment discount is actually applied during invoice settlement.

Summary

The Adjust for Payment Discount field determines whether the VAT amount originally posted on an invoice should also be adjusted when a payment discount is applied.

If the setting is enabled, the part of the payment discount attributable to VAT is posted as a VAT adjustment.

For an invoice of 1,230.00 EUR including 23% VAT and a 2% payment discount, the original VAT amount of 230.00 EUR is reduced to 225.40 EUR after the discount is applied.

If the setting is disabled, the VAT amount remains at the original 230.00 EUR.

The behavior described in this article is based on standard Microsoft Dynamics NAV / Business Central functionality. A specific implementation may include custom modifications, extensions, or changes introduced by the implementation partner. For this reason, we recommend verifying the behavior in the specific database before changing the setting and testing the change in a test environment first.

Default Safety Lead Time in Business Central – What It Is and How It Is Used

Wed, 11 Mar 2026 12:00:00 +0000

When planning production in Microsoft Dynamics NAV / Business Central, it is very important to configure individual time parameters correctly. One of the lesser-known but very useful parameters is the Default Safety Lead Time field, which can be found in the manufacturing setup.

This parameter serves as a time buffer when planning production orders.

1. Where the parameter is located

You can find this parameter in the menu:

Departments → Manufacturing → Administration → Manufacturing Setup

In this setup you will find the field:

Default Safety Lead Time

The value is entered using a date formula, for example:

1D – one day
2D – two days
1W – one week

2. What is Default Safety Lead Time used for

This parameter defines a default time buffer that is used when calculating production dates.

Its main purpose is to ensure that production is scheduled slightly earlier than the actual delivery date. This helps reduce the risk of:

production delays
logistical issues
material shortages
unexpected production interruptions

In other words, the system creates a safety buffer between the completion of production and the customer delivery date.

3. When this value is used

NAV uses the Default Safety Lead Time value only when it is not defined at a lower level.

The priority is as follows:

Safety Lead Time on the Stockkeeping Unit (SKU) Card
Safety Lead Time on the Item Card
Default Safety Lead Time in Manufacturing Setup

If the item does not have its own Safety Lead Time defined, the system will use the value from Manufacturing Setup.

4. Practical example

Parameter	Value
Customer Delivery Date	14.02.
Default Safety Lead Time	2D

When planning production, the system calculates the dates as follows:

Parameter	Result
Production Ending Date	12.02.
Buffer	2 days

This means that production must be completed two days earlier than the planned delivery date.

These two days represent a safety buffer that allows time to resolve potential production or logistics issues.

5. When it is appropriate to use this parameter

This parameter is particularly useful when:

the production process is not completely stable
small delays occur frequently
there is a logistical gap between production and shipment
you need extra time for quality control or packaging

In practice, companies often set the value to:

1 day
2 days

For specific or critical items, it is usually better to define the Safety Lead Time directly on the Item Card.

Summary

The Default Safety Lead Time field in Manufacturing Setup represents a global time buffer for production planning.

If an item does not have its own Safety Lead Time defined, the system will use this value to calculate production order dates. As a result, production is scheduled slightly earlier, which helps minimize the risk of delayed deliveries.

Correctly configuring this parameter can significantly improve the reliability of production planning in Business Central.

Lead Time Calculation in Microsoft Dynamics 365 Business Central

Sun, 01 Mar 2026 12:00:00 +0000

The Lead Time Calculation setup is one of the key parameters influencing inventory planning in Microsoft Dynamics 365 Business Central. Proper configuration ensures accurate planned receipt dates and helps prevent stock shortages.

1. What Is Lead Time Calculation?

Lead Time Calculation is a date formula (for example 7D, 2W) that determines how long it takes to replenish an item through purchasing or production. Business Central uses it when calculating dates on order lines and during planning (MRP/MPS).

2. Where Is It Set?

Lead time can be defined on multiple levels:

Vendor Card – if delivery time differs per supplier.
Item Card – default lead time for the item.
Stockkeeping Unit (SKU) – if lead time differs by location or variant.

Note: When using SKUs, the SKU lead time usually overrides the general item setting.

3. How It Works in Purchase Orders

For purchase orders, the system typically calculates the planned receipt date as:

Order Date + Lead Time Calculation = Planned Receipt Date

Additional parameters such as Inbound Warehouse Handling Time and Safety Lead Time may further adjust the final expected receipt date.

4. Practical Example

A supplier delivers goods within 10 days. In Business Central you set:

Lead Time Calculation = 10D

If a purchase order is created on March 1, 2026, the system calculates the planned receipt date as:

March 1, 2026 + 10D = March 11, 2026

5. Common Mistakes

Empty Lead Time – the system may use another level (vendor/item/SKU), resulting in unexpected dates.
Wrong Level Configuration – if planning per location, configure lead time on SKU level.
Ignoring Logistics – consider transport time, customs clearance, and internal handling.

6. Why Proper Setup Matters

Correct Lead Time configuration improves:

Accuracy of planned receipt dates
Inventory forecasting reliability
Material availability for production
Reduction of emergency purchase orders

If you need more information, please fill out the contact form or contact our sales department

Sales Order Was Posted Without a Reservation

Wed, 21 Jan 2026 12:00:00 +0000

1. Problem Description

A user posted a sales order (shipment and/or invoicing) even though no reservation was created for the item.

At first glance this may appear to be a system error, but in most cases it is standard NAV behavior caused by item setup.

2. Most Common Root Cause

Item Card → field “Reserve” is set to “Never”

If the parameter Reserve = Never is used, the system:

does not create reservations (neither automatically nor manually),
does not require a reservation during posting,
allows posting as long as inventory is available.

3. How to Verify the Setup – Step by Step

Step 1: Open the Item Card

Go to Departments → Warehouse → Items
Find the item used on the sales order
Open the Item Card

Step 2: Check the “Reserve” Field

Locate the Reserve field on the Item Card
Verify its value

Possible values:

Never – reservations are not used (posting without reservation is allowed)
Optional – reservations are possible but not required
Always – posting is not allowed without a reservation

Step 3: Check Stockkeeping Units (SKU)

If the company uses Stockkeeping Units (Item × Location × Variant), the Reserve setting may be defined there instead.

From the Item Card, open Stockkeeping Units
Check the value of the Reserve field

Note: SKU settings override the Item Card settings.

4. Why Did NAV Allow Posting?

In Microsoft Dynamics NAV, reservations are:

a planning and control mechanism,
not a technical requirement for posting.

If the item does not require lot or serial tracking and inventory is available, NAV allows posting without an active reservation.

5. Recommendation for the Future

        If reservations must be mandatory:
        set Reserve = Always on the Item Card or SKU,
or consult your NAV partner for a system customization.

    

6. Summary

If a sales order was posted without a reservation, always check:

the Item Card – the Reserve field,
Stockkeeping Unit (SKU) setup.