The three CIF fee models stop being interchangeable above about £600,000 of bid value. The decision is not a single number; it is the interaction of bid value, eligibility strength, and bursar capacity.
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In-house vs retainer vs NWNF at £500k, £1.5M, £4M?
Which model wins at borderline vs strong eligibility?
Hidden costs in each model?
Decision matrix by trust archetype?
When does the fee model itself change the score?
Worked decision matrix: at £500,000 bid value, in-house beats both consultant models on cost. At £1.5M, a retainer is the safe pick if cash exists. At £4M, NWNF is the only model that does not eat working capital up front.
Hidden cost in the NWNF model: the percentage compounds on the largest awards. Hidden cost in the retainer model: no refund on rejection. Hidden cost in-house: the project-planning score ceiling.