The phrase "occasional basis" means that something happens or is done only once in a while, or not very often.
Sentences with «occasional basis»
There is a time and place for snacks — on a very occasional basis — but snacks do not need to be an integral part of every small kid's day. (treehugger.com)
And nobody should be using coal - fired electric heat except on a rare occasional basis. (planet3.org)
First, it allows service - providers to render services on a temporary and occasional basis under their original professional title without having to apply for host State recognition of their qualifications. (newlawjournal.co.uk)