The Central Coast Mariners could be in for a horror January transfer window, with a number of players reportedly free to leave because of unpaid superannuation.

The new collective bargaining agreement for A-League players states that players can become free agents if clubs do not wholly meet the agreements of their contract, including full payments and entitlements.

The Professional Footballers Association has confirmed they are monitoring the situation and that non-payment of superannuation is a breach of a player's contract.

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