Boris Johnson has pledged to permanently protect forces personnel from "unfair" taxes in Scotland if the Conservatives win the election.
The Prime Minister says those serving in Scotland are being paid as much as £2,200 less than others in the rest of the UK.
For the past two years, the Government has temporarily paid the difference to military personnel across the services, but this announcement will make the move permanent.
"The SNP hits its citizens with a whack of extra tax every year, meaning all workers can take home less of their hard-earned wages", Mr Johnson said, who has been critical of the Scottish National Party.
"It is not fair that our armed forces based in Scotland should earn less than the personnel they serve alongside in the rest of the country."
The pledge to ensure the tax mitigation is permanent has been labelled a "cynical Tory stunt" by SNP defence spokesman Stewart McDonald.
"After a decade of imposing real-terms wage cuts, failing to invest in military housing, and missing their recruitment targets, this cynical Tory stunt adds insult to injury", said Mr McDonald.
"They have failed to implement SNP calls for wage increases, they've failed to match the SNP's tax cuts for the lowest paid members of the armed forces, and they've failed to accept the SNP's calls for better terms and conditions for serving personnel and their families", he added.