The firm will make a charitable donation after the error.
An American briefly became the world’s richest man when PayPal credited him with $92 quadrillion (£60 quadrillion).
The online money-transfer firm mistakenly credited the account of Chris Reynolds, 56, of Pennsylvania, with $92,233,720,368,547,800, before quickly correcting its error.
Mr Reynolds told the press he did not notice the slip until he opened his monthly statement.
PayPal has offered to make amends by donating a sum of money to a charity of Mr Reynold’s choice.