I am in the process of refactoring a number of rental portals I've built for a company with locations in Austria, Germany, Switzerland, and the Netherlands.

Instead of the current setting of each country site running under its own domain name:

• www.companyname.de
• www.companyname.ch
• www.companyname.at

I would love to merge them all in this way:

• www.companyname.com/de
• www.companyname.com/ch
• www.companyname.com/at

with the country TLDs doing a 301 redirect to the respective .com address.

However, I have been repeatedly told not to do this due to likely problems with SEO - the business is very SEO dependent, and being a rental chain, needs to be strong in local results.

So the question is:

• Is there an unavoidable hit in Search Engine Optimization when redirecting to a central .com domain?

• What measures can be taken to soften the blow? What comes to my mind is explicitly specifying a lang attribute in the html tag.

• Are there any other ways to specifically point out geographical location for sub-directories?