The Home Office has earmarked at least £700m to manage the arrival of migrants on small boats until 2030, according to previously unnoticed commercial plans.
Officials published the projections online last week, as Home Secretary James Cleverly flew to Rwanda to sign a new treaty to "stop the boats".
They predict the Channel crossings could continue up to 2034.
Under the plans, commercial partners would run extensive services at "permanent" facilities.
A Home Office spokesperson said it would be "inappropriate to comment" on an ongoing procurement project.
But the publicly-available information, on the government's contracts website, shows that the Home Office wants at least one major partner to help run two large facilities in Kent until at least 2030 - and potentially to 2034.
The invitation to businesses is the clearest public sign yet that officials are planning for the small boats to continue arriving.
That invitation was launched on 4 December - the day before the UK signed a new treaty with Rwanda in an attempt to kickstart a policy, already blocked by the Supreme Court, to send some cross-Channel migrants to the country.
Prime Minister Rishi Sunak says the new Rwanda treaty and linked legislation will stop small boats arriving in the UK. The Home Office has said its modelling indicates that almost all appeals against deportation would fail under the revised policy.
But Robert Jenrick, who recently quit as immigration minister, told OceanNewsUK the plan was "weak" and unlikely to work. MPs will vote on Mr Sunak's new legislation on Tuesday.
The first facility that the Home Office is asking for a partner to help run is the UK Border Force's rescue and arrivals base in Dover docks, known as Western Jet Foil.
This is a secure facility where migrants rescued from the English Channel are initially brought ashore, registered and given emergency medical treatment.
The second part of the contract covers the much larger and previously-criticised Manston centre which was designed to accommodate up to 1,600 migrants while officials work out where to house them.
"The purpose of the Disembarkation and Solas [Saving Lives At Sea centre] Centre at Western Jet Foil and the National Reception Centre at Manston are to register and process individuals arriving in the UK on small boats from across the English Channel," says the web page.
"The aim of these centres is to provide a safe and secure environment, allowing Border Force to process arrivals with dignity and respect.
"The Home Office is currently transforming the site at Manston to establish permanent, purpose-built facilities, co-ordinated by the Manston Transformation Programme."
Under the plan, the page explains, the Home Office's partners would run extensive "wrap-around" services at both locations, including catering, security and medical support.
Officials have calculated these services would cost £700m over the first six years - and contracts could be extended by a further four.
If the annual costs remained the same, the government could be preparing to pay out at least £1.16bn over 10 years - although that figure does not appear in the publicly available material.
The contract notice emphasises that the plan is still in development and is far enough advanced for potential bidders to be invited to meet officials at Manston in the new year. But they will need to keep the details of the government plans secret by signing a non-disclosure agreement.
Shadow home secretary Yvette Cooper said: "This shows even the Home Office doesn't believe Rishi Sunak's Rwanda plan is going to work. This is total Tory chaos and it's letting the country down.
"Instead of sending nearly £300m of taxpayers money to Rwanda for a failing scheme, the prime minister should be using the money to stop the criminal smuggling gangs who are organising boat crossings in the first place."
Last week it emerged that the Home Office has paid £100m more to Rwanda than previously stated - and the department's permanent secretary, Sir Matthew Rycroft, will face MPs later on Monday over the scheme's costs.
Meanwhile, Home Office modelling claims the new Rwanda policy to block courts from intervening in flights would ensure more than 99 per cent of appeals against deportation would fail, as many facing removal to the country would not be able to provide evidence that they faced serious harm.
The projections are part of a document prepared by the Home Office in March, before the Supreme Court ruled last month that Rwanda is an unsafe country for asylum seekers. The modelling, seen by the OceanNewsUK, was first reported by the Times.
