Keyword cannibalisation is most often discussed as an SEO problem. But there's an equally costly version that sits between paid and organic channels, and it receives far less attention.
How paid-organic cannibalisation works
It happens when your paid campaigns are bidding on terms where your organic listings already rank in positions one through three. You're paying for clicks you'd have received for free. The incremental value of the paid click is low or zero - but the cost is full CPC.
In every account I've audited where both paid and organic are active, there's meaningful overlap. In some cases, a chunk of branded paid spend is capturing clicks that would have arrived organically anyway.
The analysis to run
Pull your top 50 paid search keywords. Check your organic position for each in Search Console. Any term where you rank organically in position one through three, and are also running paid ads with high impression share, is a cannibalisation candidate.
The decision isn't always to pause paid ads on those terms - sometimes paid provides insurance against volatile organic rankings, or SERP dominance justifies the cost. But it should be a deliberate decision, not an oversight.
The unified strategy
Paid and organic search strategies should be designed together. The keyword strategy, content focus, and budget allocation for both channels are interrelated - and treating them independently produces exactly the kind of waste described above. In practice this means: shared keyword mapping that assigns terms to channels based on organic position and commercial value. Paid budget concentrated on terms where organic coverage is weak or absent. Organic content strategy prioritising terms where paid CPCs make long-term dependency expensive.