From The Enigma
NPL Magazine
February, 2018
LEXMAN (adapted)

The two keywords of this flat differ by a single letter and a hyphen.

I asked for a _ _ _ _ of my test results,
But, alas, my hopes were dashed.
"Your card's been rejected," is what they said,
"We'll need your _ _ - _ _ _ in cash."

Answers:

COPY
CO-PAY