The body set up to oversee compliance with social partnership agreements is due to hold talks with both sides in the An Post dispute tomorrow.
The Communications Workers Union is planning strike action at the company in pursuit of pay increases due to its members under the Sustaining Progress deal.
The Labour Court has backed An Post's stance that the money should be linked to reform of work practices.
However, the CWU rejects this on the grounds that the Sustaining Progress increases were designed to meet rises in the cost of living and were not supposed to be linked to productivity.
The union agreed to defer its strike plans last week pending an independent assessment of the cost of its pay claim.
The assessment was presented to the National Implementation Body yesterday and is due to be examined by both sides during tomorrow's talks.