you should be able to pull this off. It depends on how they are going to pay you and of course on the connections between this firm and your employer. If you are happy enough that they won't find out (bearing in mind the smallness of Dublin), then go for it. Presumably you would invoice the company you contract for, they'll pay you, and you will have to take care of the tax yourself, the tax and prsi will amount to 47% of the value, if you are a top rate tax payer - however this can be reduced substantially if you invest it in a pension before Oct 31 next.