If I update the tax amount on a general journal line after it has been calculated, where does this tax amount post to? I have been testing modifying the tax amount but the actual tax amount that posts to my tax entries is the original amount that was calculated, not my adjusted amount.
Hi @matt_sporre
This is common in Business Central.
What’s Happening:
When you manually adjust tax amount after calculation, BC doesn’t update the tax posting. The original calculated amount posts instead.
Why:
Tax calculations are tied to Tax Group and Tax Posting Group configuration. Once calculated, the tax amount is locked. Manual adjustments don’t override posting logic.
Solutions:
1. Adjust Before Posting
- Modify tax amount before posting
- Use “Recalculate Tax” function
- Post immediately
2. Reverse and Re-enter
- Post original journal
- Create reversing entry
- Re-enter with correct tax groups
- Post corrected entry
3. Fix Tax Group Configuration
- Check the Tax Group setup. Is it calculating correctly?
- Verify Tax Posting Groups map to the right GL accounts
- Recalculate after adjusting configuration
- Reference: https://learn.microsoft.com/en-us/dynamics365/business-central/finance-setup-taxes
4. Use Tax Adjustment Journal (Best Practice)
- Post separate tax adjustment journal instead
- Post to correct tax GL account
- Easier to track and reconcile
- Reference: Set up financial processes - Business Central | Microsoft Learn
Key Point:
BC posts based on Tax Group configuration, not manual adjustments. Fix the configuration, not the line.
We’ve helped BC clients optimize tax posting.
Is this true…? Why would BC allow me to change the tax amount field then, and what would the point of the “allow tax differences” on my journal batch be?
BC does allow manual tax adjustments, which is why the field is editable and “Allow Tax Differences” exists on the journal batch.
What’s Happening:
When you adjust the tax amount manually, BC accepts it. But if the Tax Group is set to auto-recalculate, it overwrites your manual adjustment before posting. So your change exists temporarily, then gets recalculated away.
Solutions:
- Enable “Allow Tax Differences” on your Journal Batch. This permits manual adjustments to post as-is without recalculation.
- Check Tax Group Configuration - Is it set to auto-recalculate? If yes, disable it for this batch so manual adjustments stick.
- Post Tax Adjustment Separately - Post the original journal, then post a separate tax adjustment for the difference. Cleaner audit trail.
- Verify GL Account Mapping - Make sure the tax GL account is correctly mapped in Tax Posting Group. Sometimes tax posts to the wrong account.
Bottom Line:
BC allows manual tax adjustments. The issue is usually the Tax Group recalculation overriding your changes. Try enabling “Allow Tax Differences” first; that should fix it.
Let me know if it works.
Please be very account rule definition (ARD) with defined code
what?? Not sure I understand