UK net migration has fallen to its lowest level since 2012, excluding the Covid-19 pandemic period. The figure comes from the Office for National Statistics (ONS), which publishes rounded long-term international migration estimates twice a year and can revise them between releases.

BBC Verify has published an interactive tracker pulling together the latest numbers on net migration, visas, asylum, small boat crossings and returns. The tracker explains exactly what each dataset measures — and what it leaves out. Here is what the data covers.

How is net migration counted?

The ONS uses the internationally recognised definition of a long-term migrant: "A person who moves to a country other than that of their usual residence for at least a year."

The published net migration figure will not exactly equal immigration minus emigration, because the ONS rounds it. Estimates are updated twice a year, and figures from official sources can be revised between publications. The tracker displays data as presented in the latest available release.

What do the visa figures include?

Visa statistics count only visas granted — not applications — and exclude visitor and transit visas where the UK is not the final destination. Each visa granted to the same person within a year counts separately, and figures record when permission was granted, not when or whether someone actually arrived.

The categories break down as follows:

• Work visas — new grants and extensions, including seasonal work, health and care, domestic worker and youth mobility routes
• Study visas — individuals sponsored by approved UK education providers, plus short-term study visas
• Family visas — joining or staying with a spouse, partner, child or parent, or coming to care for a relative
• Other — humanitarian routes such as the Ukraine Sponsorship Scheme and the British National (Overseas) route, plus EU/EEA family permits

How are asylum seekers and accommodation tracked?

The Home Office publishes figures on asylum seekers housed in hotels under the category "contingency accommodation - hotel". All other accommodation figures cover non-hotel contingency accommodation plus initial, dispersal and "other" accommodation.

The tracker measures how evenly accommodation is spread across local authorities, comparing each area's share with the UK-wide average on a five-point scale, from "less than half" the average to "more than double".

Backlog figures for people awaiting an initial asylum decision include both main applicants and dependants. Open appeals against refused applications are counted per individual; the Ministry of Justice publishes these quarterly, on a different schedule from other asylum statistics, and the figures include a small number of appeals against revocation of protection.

What counts as a small boat crossing?

Small boat crossing numbers and the average number of people per boat come from Home Office daily data. Entering the UK without permission is an offence under immigration law, but asylum seekers are generally not prosecuted if they claim asylum on arrival. Prosecutions do occur alongside other offences, such as people smuggling or re-entering after deportation.

The International Organization for Migration (IOM) collects figures on people who died or went missing crossing from mainland Europe to the UK, based on information from French and UK officials and media sources. The IOM considers these an undercount, because no official statistics exist. Figures may include deaths in the Channel itself and deaths while travelling to a crossing point.

Modern slavery data covers final decisions only, spanning human trafficking, slavery, servitude and forced labour. A separate category combines all recorded irregular arrivals not made by small boat, including inadequately documented air arrivals, detections at UK ports and other recorded detections within the UK.

How do returns and deportations work?

People denied entry at the border who then leave the UK are excluded from the returns figures. Government-involved returns fall into three groups:

• Enforced returns, including deportations — the Home Office requires someone to leave and arranges removal, usually because they have no right to remain or after a criminal conviction
• Assisted voluntary returns — the person agrees to leave and receives support such as travel documents, flights or reintegration help
• Controlled voluntary returns — departure is voluntary but formally recorded by the Home Office

Independent returns, called "other verified returns" by the government, cover individuals who left the UK without state involvement. Returns after a criminal conviction include non-British citizens convicted in the UK of any offence, or abroad of a serious offence.

How does the UK compare with Europe?

For per-capita comparisons, the tracker excludes European countries with populations under one million. Sea arrival figures combine the UNHCR European sea arrivals dashboard with Home Office small boat data. For net migration comparisons, only countries that include asylum seekers or refugees in their immigration figures are included — among them Austria, Belgium, Estonia, France, Germany, Greece, Ireland, Italy, the Netherlands, Norway, Slovenia, Spain and Switzerland. Portugal is temporarily excluded because its 2024 net migration data was unavailable; it will return in future updates.

UK population figures come from the ONS, National Records of Scotland and the Northern Ireland Statistics and Research Agency 2024 mid-year estimates; European population figures come from Eurostat as of 1 January 2024. Readers should check the latest ONS and Home Office releases directly, as all official figures remain subject to revision.