Nine in 10 appeals brought by EU citizens who have challenged Home Office decisions about their right to stay in the UK post-Brexit have been successful, new data has revealed.

The Public Law Project (PLP), which obtained the figures, said the findings raised “a number of red flags” for EU citizens “seeking to make the UK their home”.

The PLP discovered via a series of freedom of information requests that 89.5% of initial EU settlement scheme (EUSS) decisions subject to an “administrative review” by an EU citizen unhappy with their conclusions were overturned.

In just under 60% of total reviews, the Home Office refunded the £80 administration fee.

The FoI shows that 451 administrative reviews had been requested up to 12 September this year, less than six months after the scheme was launched.

Of the total 325 administrative reviews that had been decided by that date, 291 resulted in a decision of “pre-settled status” being overturned and “settled status” granted.

The PLP says this success rate is “drastically higher” than other Home Office administrative reviews, which were recorded in 2016/2017 as 3.4%.

Most, but not all, of the 3.4 million EU citizens who wish to remain in the UK after Brexit must apply to the scheme. Those who have been in the country for fewer than five years can get pre-settled status allowing them to remain lawfully in the country.

Under the system, “administrative reviews” may be requested if a decision grants pre-settled status but an applicant believes they qualify for settled status.

Some decisions have been overturned because of mistakes made by caseworkers, although the Home Office says the majority are made because an applicant has provided new information.

The PLP says the data could show a successful process in operation, demonstrating the Home Office checks are working.

Bu it “could also indicate that the automated data checks and initial decision-makers are getting things wrong more frequently,” said PLP research director Joe Tomlinson and PLP researcher Alice Welsh in a blog post on the matter.

It is also a concern because “a tribunal appeal right for EUSS decisions is still yet to be legislated for and judicial review is expensive, inaccessible, and limited to narrow legality claims, so administrative review is the primary mode of redress” available for applicants to the scheme, they added.

The Home Office said the overall number of administrative reviews “is very low compared to the 2.4m applications and 1.9m granted status by the end of October 2019”.

It also cautioned against concluding the high number of successes were because of mistakes by officials. It said the “majority of overturned decisions are not caseworker error but where an applicant provides new information”.

However the PLP said that whatever the reason, the Home Office needs to get every decision right and may have to improve its communications to ensure EU citizens apply with correct information.

Tomlinson and other lawyers are warning EU citizens not to accept pre-settled status if they feel they are entitled to settled status and to challenge Home Office decisions.

“This distinction could have a big impact on their rights to access services in the UK such as healthcare, housing and benefits,” says Tomlinson.

Last month it emerged that the proportion of EU citizens being granted “pre-settled status” in the UK has continued to rise.

Tomlinson called on the Home Office to provide greater detail about the data it provides to the public in order to help ensure independent observers are satisfied the system is not discriminatory or faulty.

“The lack of available data means it is impossible for anyone outside of the Home Office to trouble shoot. Is the system working well or not? We just don’t know,” said Tomlinson.