The company has announced the price of most post sent within the islands and to the UK will rise from 7 April.
Low Value Consignment Relief ended on 1 April 2012, but had allowed some items to be sent VAT-free to the UK.
Boley Smillie, chief executive, said the freeze aimed to help "an industry under significant pressure".
The price of a local letter will increase by 1p, from 40p to 41p, while the price of a letter to the UK will stay at 55p.
Other changes include rises for certain weights of large letters and packets sent to the UK with full details due to be released on the Guernsey Post website on Friday.
Mr Smillie said: "It's been another challenging year for Guernsey Post, but we believe we have been successful in keeping any increases to our postal tariff to a minimum.
"We are also confident that our prices remain competitive in comparison with the UK and Europe.
"As an example Royal Mail will be increasing the price of a letter for UK customers by 2p to 62p. By freezing the UK letter price in Guernsey at 55p, our rate is 7p cheaper."
The postal prices for flower exporters have been frozen by Guernsey Post in a bid to help the industry after the loss of UK tax relief.