More than 2,000 stores will be affected by the move, which is collectively worth £2.2m per year.
It marks the first increase in the payment since 2012.
The news follows an announcement made in April of an increase in payments for cash deposits from 1 August, originally scheduled for October.
National Federation of SubPostmasters (NFSP) chief executive Calum Greenhow told Better Retailing: “There is now recognition within government and within PO’s senior management that subpostmaster remuneration has to be increased in order to give the network a more sustainable future.
“We are working to ensure that substantive increases to pay are brought about via the remuneration review.”
A Post Office spokesperson told Better Retailing: “We are determined to secure and enhance the PO network for the future, ensuring that our postmasters are fairly rewarded.”
However, trade union CWU’s national branch secretary, Mark Baker, added: “This is a step in the right direction, but more needs to be done to improve rates.”