[Due for payment 2026-01-30] Expense - Tax amount in expense thread and confirm page is different

[mitarachim]

If you haven’t already, check out our contributing guidelines for onboarding and email contributors@expensify.com to request to join our Slack channel!

---

Version Number: 9.3.6-0
Reproducible in staging?: Yes
Reproducible in production?: N/A - new feature, doesn't exist in prod
If this was caught during regression testing, add the test name, ID and link from BrowserStack: #78358
Email or phone of affected tester (no customers): soidjsoijosjnisjidsj@gmail.com
Issue reported by: Applause Internal Team
Bug source: Exploratory - Significant User Experience Deterioration
Device used: Mac 26.1 / Chrome
App Component: Money Requests

Action Performed:

Precondition:

• Taxes are enabled.

1. Go to staging.new.expensify.com
2. Go to self DM.
3. Create an expense with amount 10.00.
4. Open the expense.
5. Click Taxes and change it to 5% rate.
6. Click Tax amount and change tax amount to 0.10.
7. Go back to self DM.
8. Click Submit it to someone.
9. Select the workspace.

Expected Result:

Tax amount on confirm page should be the same as tax amount in expense thread - 0.10

Actual Result:

Tax amount on confirm page shows 0.48 which is different from the tax amount in expense thread - 0.10.

Workaround:

Unknown

Platforms:

• Android: App
• Android: mWeb Chrome
• iOS: App
• iOS: mWeb Safari
• iOS: mWeb Chrome
• Windows: Chrome
• MacOS: Chrome / Safari

Screenshots/Videos

Bug7055141_1769042392295.Screen_Recording_2026-01-22_at_08.39.03.mp4

Bug7055141_1769042237256.6.mp4

View all open jobs on GitHub

Issue Owner

Current Issue Owner: @greg-schroeder

[melvin-bot]

You have been assigned to this deploy blocker because you recently merged this PR: #78358

[melvin-bot]

💬 A slack conversation has been started in #expensify-open-source

[melvin-bot]

Triggered auto assignment to @greg-schroeder (Bug), see https://stackoverflow.com/c/expensify/questions/14418 for more details. Please add this bug to a GH project, as outlined in the SO.

[github-actions]

👋 Friendly reminder that deploy blockers are time-sensitive ⏱ issues! Check out the open `StagingDeployCash` deploy checklist to see the list of PRs included in this release, then work quickly to do one of the following:

1. Identify the pull request that introduced this issue and revert it.
2. Find someone who can quickly fix the issue.
3. Fix the issue yourself.

[OSBotify]

Investigation Summary

Classification: Frontend bug
Causing PR: #78358 - fix: revert revert taxes field by @koko57 (High confidence)

Recommendation: REVERT

PR #78358 introduces automatic tax recalculation logic that overwrites manually-edited tax amounts when submitting a tracked expense to a workspace. The code does not preserve user-entered tax amounts.

Labels: Removed DeployBlocker label (backend not affected). Kept DeployBlockerCash label (App deploy remains blocked).

Evidence

PR #78358 was merged on 2026-01-21 (day before this issue was reported) and is explicitly referenced in the issue as the PR being tested during regression.

The bug occurs when:

1. User creates tracked expense with amount 10.00
2. Sets tax rate to 5%
3. Manually changes tax amount to 0.10 (overriding calculated 0.50)
4. Submits expense to workspace
5. Confirmation page incorrectly shows recalculated tax instead of preserving manual 0.10

Root Cause

The code in src/components/MoneyRequestConfirmationList.tsx lines 543-548 has a useEffect that automatically recalculates and sets the tax amount without checking if the user manually edited it. When navigating to submit a tracked expense to a workspace, this useEffect overwrites the manually-entered tax amount with a recalculated value based on the tax rate percentage.