Britain left the EU in January and continued access under transition arrangements ends on Dec. 31, meaning EU banks would not be allowed to use clearing houses such as the London Stock Exchange's LCH and ICE Clear Europe in 2021.
The European Commission declined to comment on Tuesday.
Although a low margin business, clearing is a critical foundation for global financial markets, ensuring trillions of dollars in swap trades complete safely.
London's clearing houses help cement the capital's status as the world's biggest centre for trading derivatives, adding to its historic attractiveness as a base for global banks.
Brexit has already prompted some to shift hundreds of jobs to EU hubs, and lobby groups have warned that more could leave if euro clearing shifts to the euro zone.
LCH clears the bulk of euro-denominated interest rate swaps that are used by companies across the EU to insure themselves against adverse moves in borrowing costs.
But euro derivatives clearing in London has long been a point of tension between Britain and the EU, where policymakers want euro zone activity under European Central Bank scrutiny.
The EU has acknowledged that a sudden cut-off in access could undermine financial stability as users sought to shift large derivatives positions at short notice, giving it little choice but to grant what it has dubbed "time limited" access.
The EU document, which was seen by Reuters and is out for consultation among EU states since Monday, said access would start on Jan. 1, 2021 and expire on June 30, 2022.
Industry officials expect a formal decision next week.
"This is going to be good news," one industry source said after concerns that a shorter period was on the cards.
A European Commission official had told derivatives industry officials last week that a decision to grant access would be delayed from this week to later in the month due to Brussels' concern over British moves to partly breach its Brexit treaty.
Granting temporary access is aimed at giving time for euro zone-based clearers to "further develop their capacity to clear relevant trades", the document said.
Signed by European Commission president Ursula von der Leyen, the document said the derivatives industry is also expected to develop a "clear process" to reduce exposures to systemically important clearing houses in Britain.
Access will also depend on the Bank of England cooperating "closely" with EU authorities, and on the bloc's markets watchdog ESMA having "immediate access in all situations" to all information on risks from British-based clearers.
The Bank of England has warned the EU about "multiple hands on the steering wheel" in a market crisis.
By Huw Jones