It said it rejected a proposal from Royal Mail for a number of pay options that amount to 6.7% on basic pay over two years with additional lump sums.
It hit out at Royal Mail's working flexibility proposals as "postal workers will not know what job they are performing from day to day" and at new pension proposals for being, essentially, the same as the last proposal it rejected.
Royal Mail released a statement critical of the union's stance: "Royal Mail is extremely disappointed that, despite a four week 'period of calm' to allow talks to take place, the Communication Workers Union continues to ignore the stark challenges facing the company and refuses to agree a way forward for the business.
During these talks, Royal Mail offered the CWU both a short term resolution to the dispute within the amount available for pay this year and at no extra cost to the company, as well as a longer term solution which we believe is in the interests of all our people and the business."
The company said it would be announcing its next steps in due course.