What’s this customer worth to you?

13th October 2026 |   Mark Davies MBA MSC CEng CMktr MIET FCIM

How to size a key account, from this year’s share of wallet to a decade of lifetime value.

Somewhere in your business, probably this quarter, a group of senior people will sit in a room and decide where next year’s money goes. New markets will be discussed, acquisitions perhaps, product launches. At some point, your key account – the one you have spent three years building – will flash up on a slide, and someone will ask the only question that matters: how much more is in there? If you cannot answer with a credible number, the money goes somewhere else. It is that simple.

That question has two halves, and they need answering in order. The first is near-term: what could this customer spend with you this year, and how much of it do you win? That is share of wallet. The second looks down the years: what is the whole relationship worth across every year you keep it, in money you can set beside any other investment? That is customer lifetime value. Get both right and you walk into the planning round holding the one thing that recruits senior sponsors faster than anything else, a believable statement of the prize. Neglecting this is costly. Only 8 per cent of sales organisations rate their own account planning process as very effective (Gartner, 2026), and the missing ingredient is nearly always the same: not aspiration, not relationship warmth, but a number the finance director cannot wave away.