1. move the goalposts - Verb
2. move the goalposts - Phrase
move the goalposts (third-person singular simple present moves the goalposts, present participle moving the goalposts, simple past and past participle moved the goalposts)
(idiomatic) To alter the terms of an agreement or an agreed target, or the rules of a negotiation while it is ongoing, especially in an unfair way.
This is a Government that meets its economic targets and does not move the goalposts.
We were given a moving date, and an exchange date, but the buyers kept moving the goalposts and giving us a later date.