Tolls on the Severn Bridges will be cut in January for the first time, as VAT is removed from the fees.
Cars heading for Wales will be charged £5.60 instead of £6.70, with vans paying £11.20 - down from £13.40 - and coaches £16.70, currently £20.
UK ministers confirmed it was a step towards abolishing tolls altogether at the end of 2018, as revealed in July.
Welsh Secretary Alun Cairns said tolls had been "an economic and symbolic barrier to Wales' future prosperity".
It will be the first time since the first Severn Bridge opened in 1966 that the toll has been cut.
The reduction takes effect on 8 January, the date the two crossings return to public ownership.
Motorists will also not face the usual inflation-related increase on New Year's Day.
Mr Cairns will give the news to business leaders at a meeting of the Confederation of British Industry (CBI) Wales regional council in Newport on Friday.
"For so many years, the tolls on both Severn Crossings have been seen as an economic and symbolic barrier to Wales' future prosperity," he said.
"Our decision to reduce the tolls - before abolishing them altogether - will cut costs for businesses, for commuters and tourists alike - helping boost jobs and trade in Wales and across the South-West [of England].
"This is yet another strong indicator that Wales is open for business and of the UK government's commitment to making the right decisions for Wales' future as part of a strong United Kingdom."
The UK government said estimates showed abolition of the tolls could boost the south Wales economy by £100m a year and save regular motorists more than £1,400 a year.
Michael Gough, co-owner of a haulage company in Llandrindod Wells, Powys, told BBC Radio Wales: "Every reduction is a benefit to Wales.
"However you look at it, the Severn Bridge toll is a tax on every business that is based here.
"[The cut in the toll] is a start, and we as a company are looking forward to the abolition of it at the end of the year.
"That's a large saving - even as a relatively small company based in mid Wales we spend about £1,500 a week on the tolls, so as you can imagine that would be of great benefit to us."