The comments inflamed critics of the government's handling of the complex divorce process at a time when talks with Brussels have stalled because of a row over how to manage the Irish border after Brexit, Reuters reported.
Davis has become embroiled in a long-running argument with lawmakers – including from the ruling Conservative Party – over what preparatory work the government has undertaken, and how much of it should be made public.
"There's no systematic impact assessment I'm aware of," Davis told a parliamentary committee, saying it would be more appropriate to conduct such analysis later in the negotiating process.
His remarks drew immediate criticism from lawmakers on the committee, who said Davis was contradicting his previous statement that the government had analyses of the sectoral impact that went into "excruciating detail".
"Whether it's through incompetence or insincerity, David Davis has been misleading parliament from the start," said Wera Hobhouse, a member of the Brexit committee from the Liberal Democrat party.
"It is unbelievable that these long-trumpeted impact assessments don't even exist, meaning the government has no idea what their Brexit plans will do to the country."
Parliament could have a decisive role in the Brexit process if it blocks or amends the legislation which the government has proposed to enact the divorce.
May has only a slim working majority in parliament and is vulnerable to rebellion from within her own party, which is divided over the right approach to Brexit.
Davis and his team of ministers have previously said its sectoral analysis is not a formal impact assessment – a technical document submitted to parliament – and that publishing the work it has done could undermine Britain's negotiating position.
Nevertheless, lawmakers have pressured the government into releasing a summary of its analysis to the committee. On Wednesday, they complained that the analysis given to them was incomplete and called for more detail.
"We will at some stage do the best we can to quantify the effect of different negotiating outcomes as we come up to them – bearing in mind we haven't started phase two (negotiations) yet," Davis said, referring to the second phase of talks which will focus on trade.
He said those assessments would look at the impact of different outcomes on sectors including financial services, manufacturing and agriculture.