To-Complete Performance Index (TCPI)
The To-Complete Performance Index (TCPI) is the cost efficiency the remaining work must achieve to finish exactly on budget: budgeted work remaining divided by budget remaining. A TCPI at or below 1.0 is achievable; above 1.0 means the rest of the job must outperform the plan.
Where CPI reports the cost efficiency achieved so far, TCPI answers the harder question: what efficiency does the rest of the project need? It divides the value of work remaining (BAC - EV) by the money remaining (BAC - AC).
With BAC at 1,000,000, EV at 400,000 and AC at 450,000, TCPI = 600,000 / 550,000 = 1.09: every remaining euro must buy 9% more work than planned. Note the inverted reading versus the other indices - for TCPI, at or below 1.0 is the comfortable side, because it is a required efficiency, not an achieved one.
TCPI is the reality check on optimistic recovery plans. A project running at CPI 0.90 promising to finish on budget is implicitly promising a step-change to TCPI 1.09 or better - and performance research consistently shows CPI rarely improves materially once a project is past roughly 20% complete. When hitting BAC is no longer credible, the same formula is computed against the new target instead: TCPI = (BAC - EV) / (EAC - AC).
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