What are the drawbacks associated with contractors using their own limited companies abroad?
The 183 day rule does not apply to your contractors:
The 183 day rule applies to workers who, having been employed by a company in a country (for example, the UK), are then sent to Germany (for example) to work for that company. That is, they are seconded to Germany by the company. Those workers can remain on a UK payroll/linked to the UK for a period of up to 183 days. After this point they must be registered in the German system.
Given that contractors are individuals going to work in Germany, (not linked to, seconded by, or employed by, any company), their cases are different to that above in so far as they are tax-liable in Germany, on their German-sourced income, from the very first day they work there. Recent legislation enacted in both Belgium & Germany enforces this premise.
Some contractors argue that their own limited company has in fact seconded them to Germany (and they can therefore avail of the 183 day rule as above). However, in the case of individual contractors, their centre of economic interest has moved to Germany (as they are the centre and driving force of their company) and they are therefore liable for German taxes from day one. They are also physically present in Germany and sourcing their income, directly or indirectly, from a German client.
Social Security:
Contractors using their own UK Ltd company for an extended period overseas will most likely not be adequately covered for Social Security.