It has previously been held by the Taxing Master and the Courts, that in the event a lodgement is made in a High Court case with a Circuit Court level of damages and such a lodgement (or tender) is accepted, the Plaintiff is not restricted to costs of the lower jurisdiction (see Cronin Vs Astra Business Systems Limited  3IR476).
However, most interestingly, this issue arose in a Ruling delivered on 2nd June 2011 before Master Flynn. The Defendant in this instance had submitted a tender for an amount within the Circuit court jurisdiction in a High Court case and enclosed said tender with a covering letter in open correspondence stating that the costs would be on a Circuit Court basis. It was held by the Taxing Master that this stipulation on the covering letter would be sufficient so as to restrict the Plaintiff to Circuit Court costs rather than High Court costs once he accepted the tender. Therefore, Practitioners should be aware of this when proposing / accepting a tender on such a basis.