Shared services chargeback: stop billing by headcount, start billing by what each unit uses.
A shared services centre lives or dies on whether the business units trust the bill. Allocate the centre's cost by headcount, revenue or a flat per-user fee and a unit that barely touches the service subsidises one that floods it with invoices, tickets and exceptions. The light user feels overcharged, the heavy user has no reason to behave, and the whole chargeback gets argued over instead of acted on. A consumption-based model, built on the real cost of each activity, ends the argument.
Cost and Profitability Consulting · 150+ models since 2010 · TDABC
A fair shared services chargeback bills each business unit for the activities it actually consumes, an invoice processed, a hire onboarded, a ticket resolved, rather than splitting the centre's cost by headcount or revenue. Rateable allocation makes heavy consumers look cheap and light ones look expensive, which is why so many chargebacks are disputed. TDABC produces a cost per activity, so the bill reflects real consumption and the business units can finally see and influence what they pay.
Rateable allocation rewards the heavy user.
When the centre's cost is split by a unit's size, the cost driver, transactions and their complexity, is ignored entirely. A small unit that submits thousands of messy invoices pays the same rate as a large unit that submits a handful of clean ones, and the model has no way to tell them apart. That single distortion is what turns a chargeback into a monthly argument.
Headcount and revenue reward the heavy user
Splitting cost by size means a small, high-volume, high-exception unit pays the same rate as a large, low-volume one. The driver is transactions and complexity, not size.
"Free" services get over-consumed
Bundled into a flat charge, a service has no signal to use it carefully. Low-value requests, ad-hoc reports and avoidable exceptions pile up because the requesting unit feels no cost.
Disputed bills cost more than they recover
A chargeback the units do not believe becomes a monthly negotiation. The centre spends real effort defending an allocation it cannot fully explain, and trust in the model erodes.
No transparency, no behaviour change
If a unit cannot see that its exception rate or its off-cycle requests drive its bill, it has no reason to change. A consumption-based chargeback is also a behaviour-change tool.
CHARGEBACK: BY HEADCOUNT VS BY CONSUMPTION
Illustrative. A headcount split charges two same-size units alike; a consumption split charges the heavy, high-exception unit for what it actually uses.
The bill is built bottom-up, activity by activity.
The fair charge is a capacity cost rate per resource group, times the time each activity takes, times the volume each unit generates. Each "cost per" is a TDABC output, not a guess, so the unit sees exactly which activities and which volumes drive its bill, and can act on them.
Business unit chargeback =
(invoices processed x cost per invoice)
+ (exceptions / queries x cost per exception)
+ (new hires onboarded x cost per onboarding)
+ (tickets raised by tier x cost per ticket)
+ (off-cycle / ad-hoc work x cost per request)
+ agreed share of true fixed / standby capacity
Illustrative. Each "cost per" is a capacity cost rate times activity time, so the bill reflects consumption, not size.
In the gap between a unit's size and its handling.
As an illustrative sector pattern, a finance shared services centre that moved off a headcount split found that two business units of nearly identical size were costing very different amounts to serve, one ran clean, low-exception transactions, the other generated a stream of off-cycle requests and corrections. The headcount model had charged them the same; the consumption model charged them honestly, and the heavy unit's exception rate fell once it could see the bill it was creating. The chargeback stopped being a tax and became a signal.
For the underlying allocation method, see our guide to activity-based costing.
Frequently asked questions
- What is a chargeback model in shared services?
- It is how a shared services centre recovers its cost from the business units it serves. A fair model bills each unit for the activities it actually consumes rather than splitting cost by headcount or revenue.
- Why is headcount-based chargeback unfair in shared services?
- Because cost is driven by transactions and complexity, not unit size. A small, high-volume, high-exception unit can consume far more than a large, low-volume one, yet a headcount split charges them the same.
- What is consumption-based chargeback?
- A model that charges each business unit by the volume and type of activities it generates, invoices, tickets, onboardings, exceptions, each costed with a cost-per-activity rate from TDABC.
- How do you make a shared services chargeback the business units trust?
- Build it on a transparent cost per activity, show each unit which activities and volumes drive its bill, and let it see how changing its behaviour changes the charge.
Build a chargeback the business units stop arguing with.
The Profit Check takes 12 to 15 minutes and no data upload. It points to where your allocation is most likely unfair, and what a consumption-based model would change.
- Fee
- Fixed, agreed before we start
- Duration
- 3 to 5 weeks
- Your time
- 2 to 4 hours in total
- Access
- No ERP access, no lock-in
Proof
A distributor in New Zealand. €1.335M of cost-to-serve made visible, then halved, and 830 loss-making customers brought down to 295.
Read the case study →Who you would be talking to
Miguel Guimarães, Founding Partner
Cost and profitability practitioner for 25+ years. Presented the Damco cost-to-serve case at Managing for Profit (Amsterdam RAI, December 2009), on the same programme as Robert S. Kaplan.
Call +351 910 313 731
Workshops20-21 Oct · Online, ZoomReserve a seat
Reviewed by
Miguel Guimarães
Founding Partner, Cost and Profitability Consulting
More than 150 Time-Driven ABC engagements across 11 sectors since 2010, working within the Kaplan and Anderson framework.
About the author →Published
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- 1Time-driven activity-based costing: ABC made simple and scalable
- 2Cost-to-Serve Analysis
- 3The Whale Curve
- 4TDABC vs ABC
- 5Make-or-Buy and Relevant Costs
- 6Cost-Volume-Profit (CVP) and Break-Even Analysis
- 7Customer Profitability Analysis
- 8Methods & Frameworks: how we cost, defensibly
- 9TDABC for Financial Services
- 10How to calculate cost to serve, step by step