EU citizens working at 12 NHS trusts, and students and staff from three Liverpool universities, will be invited to make applications for "settled status".
The Government said the "managed live trial" will allow officials working on the scheme to test the system using real applicants and make improvements ahead of a phased roll-out towards the end of this year.
Immigration Minister Caroline Nokes said: "EU citizens make a huge contribution to our economy and to our society and we want them to stay.
"The EU Settlement Scheme will make it easy for EU citizens to get the status they need, and when it is launched they will only need to complete three key steps - prove their identity, show that they live in the UK, and declare any criminal convictions.
Applicants will be asked to prove their identity, declare any criminal convictions and upload a facial photograph.
The Home Office will check employment and benefits data to confirm proof of residence, while all applications will be run through UK criminality and security databases.
The Government is aiming to provide applicants with a response in less than a fortnight.
After the full roll-out, people seeking settled and pre-settled status will be able to apply using an online platform.
Certain features planned for inclusion in the final scheme will not be available in the pilot phase, and those who choose to take part will have to attend an appointment with a Home Office representative who will help take them through the online application process.