Seven-time world champion Hamilton's contract with the world champions expired on the final day of December.
Mercedes team principal Toto Wolff recently indicated that a resolution is not forthcoming, admitting to arguing with his star driver on Zoom over the terms of his latest deal.
The Silver Arrows traditionally launch their new machine in February, but the sport's all-conquering team will not unveil this season's car until 2 March.
Following the postponement of the Australian Grand Prix, Hamilton, 36, is set to kick off his bid for an unprecedented eighth world title in Bahrain on 28 March.
Testing for the new campaign will also take place in Bahrain, a fortnight before the opening round.
Mercedes have become the third team to announce the launch date for their 2021 car after McLaren and Alfa Romeo revealed they will unveil their challengers on 15 February and 22 February respectively.
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