How long is a RoHS Certificate Valid for?

It's a good question!

From what little I've looked into it, there seems to be no immediately discoverable "official" expiration period for RoHS certificates provided as you say there is no change to the item's materials or in the basic design.

However the test labs that generate the reports often seem to say "5 years". I don't know if that's due to some deeper understanding of the rules or is a standard legal disclaimer for such labs or just maybe (being cynical here) they merely want to ensure future revenue doing follow-ups.

Failing a more cognizant answer from the CR4 minions, for due diligence sake I'd go ahead and request an updated RoHS COC from your manufacturers every 5 years (or 5 years from the COC's date, if present). If they don't have one, then make a note of it.

My work does not care at all about RoHS certification, so I can only speculate. But I believe that repairguy needs to make a clarification for an accurate answer. Do you do any manufacturing of these products that you sell or are you just distributing these products as they come to you from a RoHS certified manufacturer? If you do not do any fabrication work, then I would expect that the RoHS certification for the parts would not require recertification. If instead you do do fabrication then your work is what is getting certified and you would require periodic recertification.

I dont fabricate anything, however I am the first importer from a non EU country, therefore I need to hold all the relevent DOC's and hence need to know if the RoHS certificates I have, expire and if so, how long after the date of issue

The RoHS Directive does not specify that any documentation is required to prove compliancy. The industry has chosen to request signed and dated documentation from suppliers to move liability to the next group up the supply chain, should any RoHS enforcement group request documentation to show compliance and as part of a companies 'due diligence'. It shows you have at least tried to get documentation that the item is RoHS compliant vs not doing anything.

There is no time limit on RoHS complinacy documents. The item will probably change over time with Engineering Change Orders or go obsolete. You should review your environmental documentation with your supplier to ensure it is still valid, sufficiently to keep it current. The repitition of review will depend on the item and your suppliers.

The recast of RoHS is expect to go into force at the end of 2011. It includes 'Risk Management', the removal of some existing exemptions, that possible addition of an exemption and maybe the addition of 4 Phthalates (Flame Retardants).

The UK have good documentation on 'Due Diligence', see the UK National Measurement Guidance at: http://www.rohs.gov.uk/content.aspx?id=7 and related pages