I was wondering, what percentage of the marketing budget should go to the Digital Marketing Specialist? 80%? 50% 30% What's the norm?

Here's the scenario I'm looking at: It would be split between the Owner/web designer and the DMS/SEO. The Owner sells the marketing packages to the clients and builds the websites. The DMS would then do the SEM work. Would a 60/40 split be reasonable (the 60% going to the DMS)?