A UK-EU row over the so-called Brexit divorce fee will last throughout the two-year talks, according to David Davis.
The Brexit Secretary also sought to downplay fears MPs will inadvertently give the UK Government a "blank cheque" to settle any bill with the EU if they approve motions linked to the European Union (Withdrawal) Bill next week.
Mr Davis told the Commons the EU believes the UK has to pay a settlement as "that's what the law says" although he added the UK has challenged this by "testing that law".
He said: "Last week they were given a two-and-a-half-hour briefing on why we think the legal basis is flawed.
"That, I think to some extent, is why the end of that negotiating round was a little more tetchy than the one before."
Mr Davis has previously dismissed claims the UK would pay a £50 billion fee to exit the EU.
Labour former minister Chris Leslie, speaking in the Commons, also asked the Cabinet minister: "On this question of the financial settlement, can you just confirm that the Government will bring forward a separate and distinct vote in Parliament to authorise any billions of pounds of divorce bill from the European Union?
"I ask him because next Monday he's expecting the House... to vote for a money resolution which authorises in advance any expenditure, and worse to vote for a ways of means resolution to authorise 'any tax'.
"He wouldn't accept, would he, that Parliament should be giving such a blank cheque in advance without knowing what the settlement is?"
Mr Davis replied: "I think he's got that wrong, the Bill doesn't cover separation payments.
"But bear in mind one other thing we did say previously and that is there will be a vote of this House on the final settlement.
"My expectation is that the money argument will go on for the full duration of negotiations.
"The famous European line 'nothing is agreed until everything is agreed' will apply here absolutely as in everywhere else.
"So there will be a vote that the House can reflect its view on the whole deal, including the money."