The contingency measures, first reported in health journal HSJ, are being put in place due to continuing uncertainty around the volume of admissions that can be expected in January.
NHS England held a series of calls on Tuesday during which they asked local leaders to plan for a severe wave of admissions.
During the calls health bosses from NHS Trusts around England were told to identify hardstanding areas where temporary field hospitals could be sited.
The tented units would be an alternative to the Nightingale Hospitals that were set up in in larger units at the outset of the pandemic, and which have now been decommissioned or repurposed.
While NHS England is yet to formally request military support to provide the field hospitals, it is expected that the call for support from the Ministry of Defence (MoD) could go in as early as this week.
The MoD field hospitals could prove crucial as the NHS seeks to expand capacity during the Omicron wave.