100 day plan: cost savings that stick

Why the 100 day window matters

In the first 100 days, expectations are unfixed. Suppliers expect a review. Managers expect scrutiny. The board expects action. Once that window closes, every cost conversation gets framed as a cut rather than a reset - and the political cost of change rises sharply. Accelerating synergy capture by just three months brings forward roughly 25% of first-year savings (McKinsey & Company), ^{[1, 2]} which is exactly why the sequencing below matters more than the size of the eventual prize.

Weeks 1-4: baseline and prize sizing

The first four weeks are diagnostic, not delivery. The goal is a defensible view of where cost sits, where it leaks, and what is genuinely addressable in year one versus a multi-year programme. Procurement often accounts for more than 20% of total transformation impact, with 15-30% savings available over two years (McKinsey & Company), ^{[1, 2]} so this is where the baseline effort is best concentrated.

• Full spend cube - vendor, category, cost centre, GL
• Top 20 supplier contracts pulled and reviewed
• Headline benchmarks on the top 10 categories
• Sized savings prize with a confidence range, not a single number

Weeks 5-8: quick wins and mobilisation

By week eight the plan should have visible momentum. Quick wins fund credibility for the harder work in months four to twelve.

• Renegotiate the 5-10 contracts with the clearest overpayment
• Consolidate obvious duplicate suppliers
• Freeze non-essential discretionary spend categories
• Stand up a lightweight savings tracker with finance sign-off

Weeks 9-13: lock in the run-rate

The last month is about converting activity into P&L. That means finance-validated run-rate savings, updated forecasts, and a clear owner for every workstream that runs past day 100.

• Finance-validated savings tracked to the ledger, not the spreadsheet
• Policy changes (approvals, PO thresholds, preferred suppliers) documented
• Named owner and cadence for each ongoing workstream
• Board-ready readout: delivered, in-flight, and year two pipeline

What a realistic prize looks like

For a UK mid-market business with £20-100m of addressable spend, a well-run 100 day plan typically lands 3-6% run-rate savings by day 100, with another 4-8% in the pipeline for months four to twelve. The number depends more on how much has been touched recently than on sector - and top-quartile procurement functions, the ones with genuinely disciplined category management, deliver 2.4x ROI and support 30% higher margins (The Hackett Group), ^[3] which is the benchmark a plan like this is ultimately working towards.

Scaling business, rising costs and post-funding-round discipline

The 100 day plan is not only for post-deal or new CFO situations. Scale-up businesses hit a version of the same problem: revenue is growing but costs are growing faster, gross margin is drifting, and the founding-team habits that worked at £5m stop working at £30m. A post-funding-round cost discipline exercise applies the same 100 day sequence to a different starting point.

• Baseline the last 12 months of spend against revenue growth by category
• Identify categories growing faster than revenue - usually SaaS, marketing and professional services
• Introduce approval thresholds and PO discipline before headcount forces it
• Rebase supplier terms on scale-up volume rather than start-up urgency
• Stand up light procurement governance so the funding round is not spent inflating the base

For most scale-ups, this exercise buys 6-12 months of extra runway from the same balance-sheet position - without slowing hiring or product investment.

Where this connects

This overlaps directly with our cost reduction and interim procurement work, and pairs well with the Earnings improvement guide.