Utility British Gas has admitted sending one of its customers a bill for £2,320,333,681,613.
Brian Law of Fartown, Huddersfield, received the bill last month as a final demand after failing to pay an earlier bill of £59.
The sum of £2.3 trillion was apparently due for electricity supplied to Mr Law's new home in Fartown.
And the letter from British Gas threatened to take him to court unless he paid the amount in full.
I kept leaving all my phone numbers but nobody rang back
British Gas customer
Mr Law, who runs an exhibition company called Prodis Play in Leeds, had delayed paying the original bill last year because he was away on business.
A penny a day
According to the local newspaper, the Yorkshire Post, Mr Law attempted to call British Gas to resolve the matter but with little result.
"After two hours, I did get through to somebody, and said I had received this bill," Mr Law told the newspaper.
"I started reading the figure out and the girl I was speaking to said there must have been a mistake.
We had a very amiable
conversation with Mr Law about it
"Eventually, I talked to a chap who promised to sort things out and he asked me to fax the bill through.
"I did that and rang again on the Wednesday, but this gent wasn't in and neither was his manager. I kept leaving all my phone numbers but nobody rang back."
Eventually, Mr Law decided that he would only be able to resolve the matter by going to court and offering to pay a penny a week.
However, after enquiries by the press, British Gas responded, saying it was a "simple, clerical mistake".
The figure on the final demand was in fact the meter reference for Mr Law's property.
The clerical error meant that the reference ended up in the bill's total box, said a spokesman for the company in Leeds.
The company said it had "a very amiable
conversation" with Mr Law about the mix-up, adding: "he seemed to see the funny side".
Mr Law will now be setting up a direct debit arrangement to pay his future bills.
"There is certainly no question of us taking him to court or cutting off his supply," the company added.