Use Gemini in Google Drive to Compare Two Budget Drafts Without Hiding the Changes

Two budget drafts can look close while changing the assumptions underneath them. Gemini in Google Drive can compare selected files and surface differences, but the result still needs a finance owner to check before approval.

Evidence label: documentation-based and illustrative. Google documents adding Drive files as sources and comparing facts between files. The budget drafts, prompt, and output below are fictional. No Gemini session or personal test is claimed.

Reader and decision

This guide is for an operations manager preparing a quarterly budget review. The reader wants one artifact: an assumption-change table that shows what moved between the earlier and revised drafts. The decision is which changes need a finance owner’s explanation before the revised draft moves forward.

The table should preserve four things for each row: the budget area, the earlier assumption, the revised assumption, and the source passage or an explicit unknown. It should also separate a changed value from a claim about why it changed.

Access and source rules

You need a Google Workspace account with Gemini features enabled for your organization. Google says availability depends on the supported account, edition, administrator settings, and location. You also need permission to view both files in Drive. Do not upload or select confidential budget material unless your organization has approved that account and workflow.

Open Google Drive, start Ask Gemini, and use the two fictional files below as the selected sources.

q3-budget-draft.docx

Q3 operating budget draft

Budget area: Customer events
Amount: 18,000 USD
Assumption: Two regional events in September.
Owner: Marketing

Budget area: Contractor support
Amount: 24,000 USD
Assumption: One part-time support contractor for three months.
Owner: Operations

Budget area: Software
Amount: 12,000 USD
Assumption: Existing seats are renewed at the current plan.
Owner: IT

q3-budget-revised.docx

Q3 operating budget revised

Budget area: Customer events
Amount: 12,000 USD
Assumption: One regional event in September.
Owner: Marketing

Budget area: Contractor support
Amount: 30,000 USD
Assumption: One part-time support contractor for four months.
Owner: Operations

Budget area: Software
Amount: 12,000 USD
Assumption: Existing seats are renewed at the current plan.
Owner: IT

The files contain changes in the event and contractor assumptions. They do not explain why those changes were made. The prompt must keep that reason unknown.

Three steps

1. Add both budget drafts as sources

In Drive, select Ask Gemini, choose Add sources, select Add from Drive, and add both budget files. Confirm that both intended files are visible as sources before asking the comparison question.

Google says Gemini can use multiple selected source files to compare data, insights, or findings. It also says you can review the files that contributed to a response by selecting Sources below the response. Keep the source list narrow for this review so unrelated Drive material does not change the comparison.

If your Drive view offers broader search settings, leave them off for this pass or limit the search to the two selected files. The exact controls can vary by Workspace account.

2. Ask for a cited comparison

Paste this prompt into the Gemini panel:

Use only the two selected sources: q3-budget-draft.docx and q3-budget-revised.docx.

Create an assumption-change table with these columns:
- budget area
- earlier amount
- revised amount
- earlier assumption
- revised assumption
- owner shown in the sources
- change status: changed, unchanged, or unclear
- source passage or explicit unknown
- finance review question

Compare every budget area that appears in either file.

Rules:
- Preserve amounts, wording, and owners from the files.
- Use one row per budget area.
- Mark a field UNKNOWN when the selected sources do not explain it.
- Do not infer why an amount or assumption changed.
- Do not calculate savings, increases, percentages, totals, or business impact.
- Do not invent an approval status, deadline, owner, or recommendation.
- For each changed row, quote or closely identify the source passages for both versions.
- For each unchanged row, show the evidence that both versions match.
- End with a separate list of questions for the finance owner.

The instruction against calculations is deliberate. A comparison can show the source values without turning a draft into a finance conclusion.

3. Check the response against the files

For these fictional sources, an acceptable illustrative artifact looks like this:

| budget area        | earlier amount | revised amount | earlier assumption                              | revised assumption                               | owner shown | status    | source evidence                              | finance review question                         |
|--------------------|----------------|----------------|-------------------------------------------------|--------------------------------------------------|-------------|-----------|----------------------------------------------|-------------------------------------------------|
| Customer events    | 18,000 USD     | 12,000 USD     | Two regional events in September.               | One regional event in September.                 | Marketing   | changed   | Both budget files, Customer events sections  | Why was one event removed from the revision?   |
| Contractor support | 24,000 USD     | 30,000 USD     | One contractor for three months.                | One contractor for four months.                  | Operations  | changed   | Both budget files, Contractor support sections| What supports the additional month?             |
| Software           | 12,000 USD     | 12,000 USD     | Existing seats renewed at the current plan.     | Existing seats renewed at the current plan.      | IT          | unchanged | Both budget files, Software sections          | Does IT confirm the current plan still applies? |

This table is written from the fictional files. It is not captured Gemini output. The reason for each changed assumption remains UNKNOWN because neither source provides one.

The final handoff should also include:

Unknowns to resolve with Finance:
- Reason for reducing the number of customer events.
- Evidence supporting the additional contractor month.
- Confirmation that the software plan and renewal assumption are current.

Decision boundary:
The revised draft is ready for finance review when every changed row has a named question and the source values match the two files. The table does not approve the budget.

Acceptance checks

The sample passes when:

Both intended budget files are selected as sources.
All three budget areas appear exactly once.
The two changed areas keep their earlier and revised values and assumptions.
The unchanged software row remains visible.
Every row names the owner shown in the files.
Each changed row has evidence from both versions.
The sources do not claim why a change happened.
No total, percentage, savings figure, business impact, approval, or deadline is invented.
The finance questions and the UNKNOWN reason fields remain visible.

Stop and repair the source selection or prompt if Gemini adds a third file, drops the unchanged row, treats a plausible reason as a source fact, or gives a calculation the sources did not request.

Troubleshooting

Gemini uses unrelated Drive material: start a new conversation, add only the two budget files, and check the selected source list before asking again.
One file is missing: confirm that your account can open the file in Drive. Google says you need permission to access a file before adding it as a source.
The output shows only one version: ask for both the earlier and revised passage for every budget area, then inspect the Sources list below the response.
The response invents a reason for a change: ask it to replace the reason with UNKNOWN and name the exact source passage that supports any explanation.
The controls are different: use the current Google Workspace help for your account. Google notes that Gemini availability and controls can vary by organization and location.
The response cites a file that does not support a row: open the cited file, compare the quoted passage, and keep the row unresolved until a finance owner checks it.

Limits and decision

Gemini can compare selected files, but Google warns that generated responses can be inaccurate and that even listed sources need checking. A source citation does not establish that a budget change is sensible, approved, or complete. Keep the original files, comparison, open questions, and finance decision together.

TRY this on fictional or approved budget drafts. SKIP using the table as approval or as a substitute for finance review. USE it as a change register that makes the next human questions easier to answer.

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Sources

Evidence label: Documentation-based and illustrative. The budget files, prompt, table, unknowns, and decision boundary are fictional teaching material. No Gemini execution, finance approval, or Cihan test is claimed.