Ministers have said that they will test what the law -- expected to get final approval on Monday -- requires of them. Prime Minister Boris Johnson has been warned that he could face legal action for flouting it.
The government has described the law, which would force the PM to seek a Brexit delay if MPs don't approve a new deal or no deal by 19 October, as "lousy".
MPs will seek to press ministers on the issue later in the House of Commons.
Downing Street confirmed that the expected prorogation, or suspension, of the Parliament until October 14 will begin at the end of Monday's sitting.
It means MPs will not get another chance to vote for an early election until after then, meaning a poll would not be possible until the end of November at the earliest.
One plan reportedly under discussion to get round the Brexit delay legislation is to ask a sympathetic European Union member to veto an extension.
Another potential option would be to formally send the extension request mandated by the new law.
However, Lord Sumption, a former judge of the UK's Supreme Court, said such a ploy would not be legal because the legislation compels the Prime Minister to seek an extension.
"To send the letter and then try and neutralise it seems to me to be plainly a breach of the act," he told BBC Radio 4's Today programme.