A family bakery chain has joined a march on Downing Street in protest at the introduction of the "pasty tax".
The UK government is planning to introduce VAT on products in bakeries that are heated to bring them in line with other hot takeaway foods.
The owners of Llanelli-based Jenkins Bakers believe the 20% VAT will deter customers from buying their pasties at a time of economic hardship for many.
A Treasury spokesman said it was closing a loophole in VAT payments.
The company's production base is at Troestre industrial estate, where 70 of the company's 300 employees work.
'Difficult economic climate'
Jenkins Bakery began life in 1921 as the Unique Cafe in Llanelli's New Dock Road.
Nowadays, its chain of 25 shops in south and mid Wales sells 50,000 corned beef pasties every week.
However co-owner David Jenkins and his staff said they were worried the VAT rise, which will push the price up from 95p to £1.14, will deter customers from buying once the £1 barrier is breached.
Mr Jenkins said: "It's grossly unfair to ask the consumer to pay 20% extra for the product simply because it's hot or warm.
"We live in a very difficult economic climate. A lot of our customers are on very tight budgets and they can't be expected to pay the extra amount. It's an unfair tax."
Petitions in each of its shops have been signed by customers, some of whom are angry at the VAT changes.
Other bakers from across the UK joined the march, including High Street chain Greggs.
A Treasury spokeswoman said: "The Budget closes loopholes and addresses anomalies to ensure a level playing field, including on hot takeaway food.
"In fact, VAT is already paid on over 90% of all hot takeaway food.
"And HMRC estimate that VAT is currently paid on around 40% of hot meat pies, pasties and sausage rolls."