TBM Modeling Guide
A standards-based, tool-agnostic playbook for designing, building, validating, operating, and evolving a TBM cost model, written against TBM Taxonomy 5.0.1. It stops at the cost model; insight generation, dashboards, and use-case enablement belong to companion resources.
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One standard, one model you can explain
The guide turns modeling decisions into a phased practice, from a defensible first Finance View to complete Solution TCO and Consumer attribution.
Shared language
Finance, Technology, and Business use standard Taxonomy names.
Extend, don’t restart
Each validated View builds on the same model.
Defensible numbers
Mappings are documented and every layer reconciles.
Governed from day one
Ownership, change control, and data quality travel with the build.
Where should you start?
The TBM Administrator is the primary builder, but each reader has a useful route through the guide.
Executive
Your job:
Sponsor and decide; you do not build. Set direction, fund a phased effort, and judge whether the model can be trusted.
Read:
DSG.1 to DSG.5, Part 1 (the WHY), and the opening section of Parts 4 to 6, which state what each View delivers and for whom.
Do:
Name a TBM Administrator with recorded decision rights. Approve a written value target. Unblock Finance, Procurement, and HR data. Make reconciliation the acceptance test for each View.
Watch for:
Pressure to model everything at once. A Finance View alone is a legitimate stopping point; later Views extend it, not rebuild it.
Brand-new practitioner
Your job:
Build one small, defensible Finance View and learn the vocabulary once, correctly.
Read:
The Taxonomy 5.0.1 Whitepaper and Executive Overview first. Then DSG, Parts 1 to 4, and Part 7 before any build. Work through Appendix F, a complete Finance View. Skim Parts 5 and 6.
Do:
Write the value target. Map the Chart of Accounts with Appendices A and B, tag the GL, and prove Cost Pools plus documented exclusions equal the GL. Track Misc Costs. Document as you go.
Watch for:
Picking tools or pulling data before the value target. Building the optional Enrichment Layer before tagging is stable. Treating fallout as failure.
Practitioner, 3 to 5 years
Your job:
Audit and extend a model you likely already run, using the guide as the standard to measure it against.
Read:
Skim Parts 1 to 3 for vocabulary and boundary rules. Go deep on Parts 5 and 6, Part 7, and Appendices C, D, and E. Keep Appendix G open for terms.
Do:
Rate each Tower Good, Better, or Best and replace policy-based splits with evidence. Move Solution mapping from Crawl toward Run where data supports it. Test chained Solution costs for loops and double counts. Add version log, change control, and audit.
Watch for:
Maturity follows the model and its value target, not tenure: one model can be Accelerating while another is Ramping. Undocumented changes to published logic.
Follow each dollar through the model
Financial Source Data is tagged into Cost Pools, allocated through Towers and Solutions and attributed to Consumers. Optional enrichment adds useful detail after tagging is stable.
One cost path, three build Views, governed throughout
Tagging identifies records. Allocation distributes cost. Attribution assigns completed Solution TCO to Consumers. Lettered badges mark the Appendix to open at that step; F, G, and H support the whole guide.
Each layer is a different lens on the same total. Costs are routed and attributed, not added together across layers. Complete and validate one View before extending the next.
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What each part helps you do
Parts 1 to 3 establish intent, language, and data. Parts 4 to 6 build the Views. Part 7 governs the model from the first rule onward.
Modeling Considerations
The planning basis, set before any data is touched.
- Plan top down: WHY (Value Driver and Outcome), then HOW (the TBM Model), then WHAT (Foundations).
- Write a value target: driver, outcome, stakeholder decision, output, timeframe, owner, acceptance criteria.
- Build an MVP: phased roadmap, layers activated one at a time. Maturity is judged per value target. Name a TBM Administrator early.
Modeling Concepts
Shared vocabulary and mechanics. No build steps.
- Tagging identifies; allocation distributes. Tagging classifies without moving cost; allocation moves cost by a rule.
- Five methods: Direct, Weighted, Usage-Based, Activity-Based, Hybrid. Choose by evidence available, not sophistication.
- Also defined: model objects, fallout (monitored, never hidden), timing, and mapping logic. The three Views overlap.
Data Foundations
What data the model needs, its condition, and its preparation.
- Minimum input: one Financial Source Data type (GL, Budget, or Forecast). GL actuals are the default start.
- Supporting sources: Chart of Accounts, cost centers, labor, vendors, contracts, POs, assets, cloud billing, non-cost volumes (see Appendix A).
- Readiness: assess completeness, validity, reconciliation, timing, ownership; normalize identifiers. Unmapped cost is fallout.
- Lenses: OpEx/CapEx, fixed/variable, Run/Grow/Transform, Governed vs. Shadow are tags, not mechanics.
Building the Finance View
Financial Source Data into Cost Pools, then the Enrichment Layer.
- Seven-step build: scope, agree reconciliation, map the Chart of Accounts, extract GL and budget, tag, populate enrichment, validate.
- One-to-one mapping: each account maps to one Cost Pool and Sub-Pool (Appendix B). Unclear accounts go to a tracked Misc Costs list.
- Supplemental tags such as OpEx/CapEx go on the same record in the same pass. They are not the Enrichment Layer.
- Validate: Cost Pools plus documented exclusions equal the GL exactly; Misc Costs stays under a threshold.
Building the Technology View
Cost Pools into Resource Towers, then into Solutions.
- Function only: Towers classify what a resource does. Start with Tech and non-Tech cost centers (exposes Shadow Technology), then other signals.
- Plan the passes: score candidate fields, run each approach, keep one mapping set per source record (splits sum to 100%). Rate each Tower Good, Better, or Best.
- Solutions: Supply Path and Investment Path feed a small Solution Portfolio. Start with the top 10 to 20 applications. Towers have no consumers; Solutions do.
- Guardrails: Solution cost is Direct + Investment + chained Indirect. No loops; indirect cost is not additive at roll-up.
Building the Consumer View
Solutions completed, then attributed to Technology Consumers.
- Solutions first: map Tower cost to Solutions in Crawl, Walk, or Run passes. Unmappable cost stays a visible Shared/Unassigned balance (under 5% is common), never spread evenly.
- Sign-off before attribution: the Solution Owner signs off TCO that reconciles to the Towers, with no double counting or loops.
- Attribution: direct for one Consumer; otherwise measured use, operational driver, proxy, even spread last. Shares sum to Solution TCO.
Modeling Governance
Sustaining, auditing, and maturing the model. Read it first, not last.
Part 7 governs the model from the first tagging rule, and the TBM Administrator owns it. Core controls are decision rights, escalation, one documentation set, version log and change control, fallout thresholds, and audit. Maturity (Ramping, Accelerating, Innovating) spans modeling depth and analytical breadth.
What the Appendices hold
A through E are used at specific steps in the flow. F, G, and H support the whole guide.
Data Sources
Critical identifiers, baseline fields, formats, and normalization notes for every source, by layer.
Cost Pool Tagging
GL account patterns and keywords by Pool and Sub-Pool, boundary cases, exclusions, mapping fields.
Allocation Methods
Six allocation patterns graded Good, Better, Best, applied to each layer transition.
Tower Mapping
Tower mapping fields, a scored plan for sequencing passes, and detail for each approach.
Solution Mapping
Fields, tags, controlled values, and validation rules for Crawl, Walk, Run, Investment, and chained cost.
Worked Example
One Finance View MVP end to end, from value target and GL extract to reconciled Cost Pool reports.
Glossary
Terms by topic with source attribution, abbreviations, and an index to the governing section.
GenAI Prompt Set
A setup prompt, intake template, and 11 task prompts. The assistant proposes; owners validate.
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Authors and Contributors
The following individuals contributed to the development of the TBM Data Architecture and Strategy Guide. The guide is governed by the TBM Council Standards Committee, which reviews it at least annually.
Matt Erickson
Director, TBM Standards and Practice
TBM Council
Justin Mann
Head of Standards, Research, & Education
TBM Council
Matt Temple
Product Manager
IBM
Stephanie Roe
TBM Strategic Advisor
RegoConsulting
Matthew Hall
VP Customer Success
Nicus Software
Gregory Nutt
Sr. Customer Success Manager
MagicOrange
Josh Roberto
VP North America Operations
Yarken
Jeff Bartelli
Content Director
TBM Council
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Feedback, corrections, and content requests are welcome: standards@tbmcouncil.org
