Microsoft and Yahoo have begun the migration of Yahoo Search Marketing accounts in the UK, Ireland and France to Microsoft adCenter. This is, of course, part of the “Search Alliance” between the two companies, with Microsoft powering Yahoo Search, both on the organic side of things, as well as on the paid side.

The transition has been complete in the US, Canada and India on the paid side. For organic, it’s already complete globally.

UK advertisers will get access to the combined audience in April, Microsoft says. The company expects to ramp up Yahoo traffic to the adCenter platform by March 19. The transition is expected to be complete by the end of April (in the UK, Ireland and). The entire Yahoo paid search volume is expected to be transitioned to adCenter within two weeks of March 19.

“Yahoo! Search and France Bing will soon offer a competitive search offering that provides advertisers both quality audiences and opportunities to leverage strategic partnerships to efficiently deliver a strong return on investment,” says Microsoft’s Cedric Chambaz. “This means our advertisers are now just a couple months away from benefiting from the new joint audience. By then, you will be able to advertise on the full Yahoo! Search, Bing and their partner networks traffic through your adCenter campaigns.”

In the meantime, Microsoft suggests getting an understanding of the new editorial policies, adjusting your budget for increased traffic and adjusting your bid strategy to maintain competitiveness.

Chambraz says that in the coming weeks, the Microsoft Advertising blog will publish more in-depth recommendations.