You can write a cheque on anything you want and anyhow
You can write it, but whether it is negotiable is another matter. The banks are not obliged to accept cheques written on just anything. They may levy an extra charge or refuse it. They usually impose limitations or additional fees in their standard terms and conditions for not using the bank's pre-printed stationery.
The negotiable cow is the common name of a fictitous legal case known as Board of Inland Revenue v Haddock (heard jointly with R v Haddock) written by the humourist A. P. Herbert for Punch magazine as part of his series of Misleading Cases in the Common Law. The case did evolve into something of an urban legend, and periodically assertions are made that it was a true case. Another Herbert story concerned a cheque written on an egg.
Don't forget to write the word "pounds" after the numbers
"Numbers"? There is a box with a £ sign for the amount in figures; but of course for the amount in
words it is best to avoid writing "dollars". Many UK banks would treat a cheque with £47.99 in figures and "Forty seven dollars and ninety nine cents" as being negotiable for £47.99, but it could be returned.
prevent fraud by "closing" the amount.
I fill up the blank space to the right of the amount in figures with a double line like this
£47.99======
Some people write the word "only" after the amount in words e.g.
Fifty seven pounds and forty six pence only
Others fill up any blank space left with a line.
Some people write the pence amount as a fraction thus
Ninety nine pounds and (or &) 99/100