Alex Rowley will tell delegates in Brighton that cutting the tax on flights will prompt the Conservative administration in London to do the same, damaging the environment and wiping out any benefits to business and tourism.
The agreement between the Tories and the DUP commits to reviewing Air Passenger Duty, the equivalent of Air Departure Tax in the rest of the UK, with the DUP manifesto calling for the levy to abolished entirely.
Mr Rowley will say the SNP should turn their attention to using devolved powers to increase Child Benefit rather than providing “a tax cut for the airlines that will benefit the richest the most”.
The interim Labour leader addresses conference today in place of Kezia Dugdale, who resigned suddenly last month.
The two candidates to replace her, MSPs Anas Sarwar and Richard Leonard, will face off in a hustings event on Tuesday, with controversy over Mr Sarwar’s business interests likely to resurface.
The Glasgow parliamentarian and former MP signed over control of a shareholding in his family’s wholesale company believed to be worth several million pounds to his children at the weekend, following criticism of the company paying the minimum wage rather than the voluntary living wage.
“We need to provide this next generation of Scots with better opportunities than the last by investing in education, training and skills,” Mr Rowley will tell delegates.
“And we need to renew our commitment to the public services that look after us from cradle to grave – the welfare state and the NHS.
“That means being honest about what we have to do to pay for these services and, as Labour, making the argument that our duties to each other mean that we can afford to pay a little more.
“Not like the Tories in Scotland, or like the SNP Government that only has one tax policy.
“The SNP can’t have a serious debate on tax if its only policy kicks off a race to the bottom against a UK Tory government, propped up by the DUP, who are desperate to see that tax abolished.
“The SNP faces a choice - work with Labour to use the tax powers to protect public services - or give Philip Hammond and Arlene Foster the excuse they are looking for to give the richest yet another bonus.”
Mr Rowley will add that Scotland “can make that difference at the next election” and help put Jeremy Corbyn into 10 Downing Street.