In the letter to Ms Reeves, Kate Nicholls, chief executive of UKHospitality, said: “We recognise the fiscal and economic challenge that you face: you are steering the economy at a moment of profound difficulty, and you have our support in doing so.
“However, the changes to the NICs threshold are not just unsustainable for our businesses, they are regressive in their impact on lower earners and will impact flexible working practices which many older workers and parents rely upon.”
The letter’s signatories warned the threshold change was particularly damaging given the hospitality sector’s reliance on part-time and low earning employees.
They said many staff members would be dragged into the tax bracket for the first time and estimated the resulting cost could be four times higher than the change in the headline rate.
The letter also branded the tax “regressive”, with National Insurance contributions for a part-time worker on minimum wage rising by almost 75pc, compared to just 13.6pc for a person earning £100,000.
It added: “Lower earners’ wages will rise more slowly as a result, and some jobs on the minimum wage will become unviable.”
The hospitality chiefs warned that companies were unable to pass the higher costs onto customers, who have already been hit by rising living costs.
They wrote: “Instead, many businesses would have to reconsider investment and drastically cut jobs and reduce the hours of team members.
“Without action, many businesses will be forced to reconsider their growth plans, and many smaller venues may be at risk of closure, risking future job creation in communities up and down the country.”
Ms Reeves has faced a fierce backlash from businesses over her Budget tax increases amid fears they will add hundreds of millions of pounds in costs.
The Chancellor has defended the tax raid, insisting the burden fell on employers rather than working people.
But the Office for Budget Responsibility (OBR) has warned these costs will be passed on to workers through lower salary increases and higher prices.