Kenneth Graeme Aitken, 66, died of a suspected heart attack in March after being sent home in his pyjamas from A&E with a packet of paracetamol.
His widow, Wendy, has now been sent a bill for £25.30 by NHS Fife to cover the taxi fare. The letter to the dead OAP gave him the option to "pay in person".
Mrs Aitken, from Dunfermline, yesterday described the letter as "dreadful" and "very upsetting". It was addressed directly to Mr Aitken and written by Barrie Higgins, facilities manager at Victoria Hospital, Kirkcaldy, and headed "recharge of taxis".
It states: "On the 14.03.14 a hospital taxi was arranged to enable you to return home after attending the Accident & Emergency Department of the Victoria Hospital, as you'd had no funds with you.
"The cost of the taxi was £25.30. This was made as a loan and I would be grateful if you could arrange to make the repayment at your earliest convenience."
Mrs Aitken said: "It's dreadful, very upsetting."
NHS Fife said in a statement: "This was the result of a clerical error. We have written to Mrs Aitken to offer our sincere apologies."
The board said the issue was subject to a "full and independent review".