Budget scenario modeler

An LLM-assisted budget scenario modeler turns raw business requirements and procurement history into multiple draft budget views, each with a TCO-style breakdown by cost category. The output is a comparison set finance can review, not an approved plan. Each line item should trace to a requirement row, a historical spend record, or an explicit blank when neither source exists.

Speed is the primary outcome. Planners stop rebuilding the same spreadsheet shells every planning cycle and spend review time on assumptions, not copy-paste. Scenarios remain draft until finance signs off. Nothing in the modeler replaces the approval workflow in ServiceNow, Apptio, Workday, or SAP; those systems still hold authoritative budgets, actuals, and workflow state.

Start with structured requirement input, not a blank template. If requirements live in workshop notes, email threads, or slide decks, run them through requirements extraction from stakeholder input first so each need has a stable row ID, owner, and priority. Unstructured prose makes citation impossible later.

Pull procurement and run-rate history for the same scope window finance uses in planning. Include contract renewals, license true-ups, cloud consumption, professional services, and hardware refresh cycles already in your ITFM or ERP ledger. Align the time horizon with your demand and capacity forecast so headcount-driven and workload-driven costs sit in the same planning period.

Define two to four scenario frames before generation: for example, status quo, deferred refresh, accelerated migration, and vendor consolidation. Name the frames in business terms, not model jargon. Specify which cost categories each frame may change (licenses, labor, infrastructure, transition) and which must stay flat unless history supports a move.

Illustrative example: A portfolio lead models FY27 infrastructure spend for three business units. Requirements list 42 rows from a Q3 planning workshop. Procurement history covers 18 months of license and cloud invoices tagged to those units. The modeler receives both files plus scenario frame names. It does not receive an approved budget target.

Ask the modeler to produce one worksheet per scenario frame. Each row should show: cost category, description, amount or blank, requirement cite (row ID), and history cite (invoice period, PO, or contract reference). Totals roll up by category and by business unit.

Use total cost of ownership calculator logic as the breakdown schema: acquisition, recurring run-rate, labor to operate, and transition costs where the frame implies change. Keep categories consistent across scenarios so finance compares like with like.

When a line has no matching history, leave the amount empty and note "no source." Do not interpolate from peer units or prior-year growth unless finance supplies that assumption as an explicit input row. When a requirement has no cost line yet, show the requirement cite with a blank amount rather than inventing a placeholder.

Review citations before sharing. Spot-check five to ten rows per scenario: open the requirement row, open the history record, confirm the description still matches. If a cite is wrong, fix the source data and regenerate that scenario block rather than hand-editing amounts in the draft.

Finance retains the approved budget, the variance narrative, and the sign-off trail. The modeler accelerates first drafts and sensitivity views; it does not post journals, commit spend, or trigger requisitions.

Treat every generated scenario as pre-approval. Route the chosen frame through your normal ITFM or ERP workflow in Apptio, Workday, SAP, or ServiceNow Financial Management, depending on where your organization records plan versus actual. Attach the scenario export and the citation index as supporting evidence, not as the system of record.

Do not auto-approve. Some tools can push plan versions forward when thresholds pass; disable that path for LLM-generated drafts until a named approver accepts assumptions in writing. Blank lines are intentional gaps for finance to fill, not signals to skip review.

When a scenario includes application retirement or consolidation, pair it with retirement cost-benefit reporter output so savings claims stay tied to decommission steps finance has already validated. The scenario modeler should not invent a savings percent. If retirement benefits are unknown, show gross new spend only and leave net savings blank.

Scenario with no history cite. A line shows a dollar amount but no procurement reference. That usually means the model filled a gap from pattern matching. Reject the row, mark it blank, and either add history or add a finance-owned assumption row with its own ID. Amounts without cites do not belong in a draft shared outside the modeling team.

Treating the draft as approved. Teams under deadline pressure sometimes paste scenario totals into board slides. Without workflow sign-off, actuals will diverge and traceability breaks. Label exports "draft, not approved" and keep version IDs on every file.

Inventing a savings percent. Consolidation and cloud migration frames tempt the model to imply "30% savings" without decommission proof. Require every reduction line to cite retirement scope or a finance assumption row. If neither exists, show cost increase or neutral spend only.

Misaligned horizons. Infrastructure scenarios that ignore the demand and capacity forecast window produce license lines that contradict headcount plans. Reconcile unit counts before regenerating.

Duplicate requirement rows. When extraction merges two stakeholder asks into one line, citations look clean but scope is wrong. Deduplicate requirements upstream, then rerun scenarios.

Organizations already running ServiceNow, Apptio, Workday, or SAP should treat the modeler as a drafting layer on top of exports from those systems, not a replacement. Export requirement registers and spend actuals in the formats your ITFM team already uses. Import finished scenarios back as attachments or plan versions only after finance review.

Apptio and similar ITFM suites often own scenario comparison UI; use the LLM draft to populate first-pass cost lines and citation columns, then let specialists refine in the governed tool. Workday and SAP environments should keep chart-of-accounts mapping explicit in the prompt so generated categories map to valid plan lines. ServiceNow shops can link requirement cites to demand records if those IDs exist in the CMDB or SPM module.

Keep vendor references at the class level. Do not rank tools or claim feature parity. Your stack dictates where drafts land; the modeling practice stays the same: cited inputs, multiple frames, blanks where sources are missing, finance approval before commit.