Sunk Cost: The Money You Should Stop Defending
We have already spent four hundred thousand on this. It is the most common sentence in a struggling project review, it is always true, and it contains no information about what to do next. The money has gone. It will have gone whether the project continues, pauses or stops this afternoon, and nothing anyone decides in the room can bring it back.
Sunk cost is money already committed and unrecoverable. The principle is simple enough to state in a line and extremely difficult to apply in a room full of people whose reputations are attached to the spend. Section 2.4.1 of the PMBOK® Guide Eighth Edition sets out the financial concepts a project works with, and this is one of the few where the technical point and the human behaviour pull in opposite directions.
Why the instinct is so strong
Accountability feels like it attaches to the spend. A manager who recommends stopping expects to be asked what the organisation got for its money, and the honest answer is often a lesson and some reusable work. Continuing defers that conversation, and deferring it is comfortable in a way that is very hard to resist when the alternative is a difficult meeting this month.
Commitment becomes identity. People who have argued for a project, staffed it and defended it in front of a board do not experience stopping as a neutral financial decision. The effort spent building support is itself a cost that feels as though it would be wasted, and it makes advocates of the people best placed to see the problem.
Accounting sometimes makes it worse. Where project spend has been capitalised, stopping can mean writing it off against this year's result, while continuing keeps it on the balance sheet. The organisation's reported position genuinely does look better for a while if the project carries on. That is a real consideration and it belongs on the table openly, not as an unspoken reason dressed up as delivery optimism.
The question that replaces it
From today, what does finishing this cost, and what will the organisation have when it is finished. Both halves need current figures, not the ones in the original business case, and the second half is usually where the honest answer has changed: the benefit that justified the work may have shrunk, arrived another way, or stopped mattering.
Then the comparison, which people skip. That remaining spend has other uses, including projects currently unfunded because this one is consuming the budget. A project worth finishing on its own terms can still be the wrong place for the next tranche of money, and a sponsor is entitled to see that comparison rather than a single yes or no.
Stopping has its own costs and they belong in the calculation honestly: contract exit terms, the write-off, redundancy or redeployment, the cost of the problem the project was meant to solve continuing unsolved. A stop case that pretends stopping is free is as unreliable as a continuation case that ignores the remaining spend.
Four hundred validators in a store room
A regional bus operator began replacing its ticketing hardware, buying validators for its whole fleet ahead of a phased installation. Roughly a third were fitted before contactless payment behaviour shifted faster than anyone had planned for and the operator's parent group committed to a new account-based system that made the remaining units redundant.
The programme continued for another five months. The argument was that the units had been paid for, that leaving them in a store room would look negligent, and that the installation cost per vehicle was modest. What that argument left out was the engineering time, the depot downtime and the fact that every fitted unit would be removed again inside two years, at a cost per vehicle not far short of the fitting cost.
The decision was eventually made by a new finance director, who asked a single question at his first review: what do we get for the money we spend from here. Nobody had a good answer. Installation stopped that week, the unfitted units were sold on to a smaller operator at a loss that was painful and much smaller than the alternative, and the depots went straight to the new system. Recognising when a continuation argument is really an argument about the past, and putting the forward case in front of a sponsor in a way they can act on, is financial judgement that Omega's PMP® Exam Preparation works through case by case.
Making stopping a respectable outcome
Set the review points before there is anything to defend. A business case that names the conditions under which the project would be halted, agreed when everyone is optimistic, gives a future review something to check against. Reaching a pre-agreed condition is a fact, and facts are easier to act on than judgements formed under pressure.
Separate the decision from the people who made the original one. A sponsor deciding whether their own project should continue is being asked to do something difficult and unfair. A different pair of eyes, with the authority to say stop and no history to protect, changes the quality of the answer considerably.
Salvage deliberately. Work already done has residual value: analysis, requirements, supplier relationships, a proven design, an understanding of the data that nobody had before. Recording what survives turns a stopped project into an investment that partly paid, and it makes the next stop decision in that organisation easier to take.
For a PMP® candidate, a justification in a scenario that refers to what has already been spent is worth noticing. A description in which a team argues for continuation on the strength of prior investment is describing a decision being taken on the wrong basis, and the response worth considering is a current assessment of remaining cost against remaining benefit.
The exercise takes an hour and can be done alone. Write down what completing the work will cost from today, what the organisation will have at the end, and what else that money could fund. If the answer makes you uncomfortable, you have learned something worth knowing while there is still budget left to act on it.
Interested in going further?
Putting a forward-looking case in front of a sponsor who is emotionally invested in a project is one of the harder conversations in delivery, and it is a learnable one. Omega's PMP® Exam Preparation covers business case review, financial judgement and governance decisions together.
The PMBOK® Guide Eighth Edition is the reference for the financial concepts behind continuation and closure decisions.
Ad · Amazon affiliate link.
References
A124: Cost Is Not the Same as Value
A125: Budget vs Cost Baseline vs Funding
A183: Cost-Benefit Analysis: Why the Cheapest Option Is Not Always Best
A123: The PMBOK 8 Finance Performance Domain: What It Really Covers
A047: Sustainability vs Cost: How Should a Project Manager Decide?
PMP and PMBOK are registered marks of the Project Management Institute, Inc.
