The transfer window is the period during the year in which a football club can transfer players from other countries into their playing staff. Such a transfer is completed by registering the player into the new club through FIFA. "Transfer window" is the unofficial term commonly used by the media for the concept of "registration period" as described in the FIFA Regulations on the Status and Transfer of Player. According to the rules, each national football association decides on the time (such as the dates) of the 'window' but it may not exceed 12 weeks. The second registration period occurs during the season and may not exceed four weeks.

The transfer window of a given football association governs only international transfers into that football association. International transfers out of an association are always possible to those associations that have an open window. The transfer window of the association that the player is leaving does not have to be open.

The window was introduced in response to negotiations with the European Commission. The system has been used in many European leagues before being brought into compulsory effect by FIFA during the 2002–03 season.English football was initially behind the plans when they were proposed in the early 1990s, in the hope that it would improve teams' stability and prevent agents from searching for deals all year around, but by the time it was eventually introduced they had to be persuaded that it would work.However, the exact regulations and possible exceptions are established by each competition's governing body rather than by the national football association

Current schedules and exceptions[edit]
FIFA regulates in general that there shall be two windows, a longer one (max. twelve weeks) in the break between two seasons and shorter one (max. one month) in the middle of a season. The specific periods depend on the league's season cycle and are determined by the national football authorities.

Most major European leagues commence in the second half of the year (e.g. August or September) and stretch over two calendar years to the first half of the next year (e.g. May), resulting in a close season window in the Summer ending in August, and a mid-season window in January.

The periods are different when a league runs throughout a single calendar year, as in most Nordic countries due to weather constraints, Major League Soccer due to both weather and competition from other locally popular sports (most notably American and Canadian football), or as the traditional season in the Southern Hemisphere. The first window generally opens from 1 March until midnight of 30 April, followed by the in-season window from 1 to 31 August.

Pre-season window & Mid-season window
1 January – 31 March & 1 – 31 August: Sweden, Norway
8 January – 2 April & 16 July – 13 August: Japan
21 January – 15 April & 27 June – 27 July: USA/Canada
1 March – 30 April & 1 – 31 August: Finland
1 July – 31 August & 1 January – 2 February: France, Germany, Italy, Spain, Scotland
11 June – 1 September & 5 – 31 January: Denmark
1 July – 31 August & 1 – 31 January: England
1 June – 31 July & 1 – 30 November: Australia
1 December – 31 January & 1 – 30 June: Kenya
9 June – 31 August & 3 – 31 January: Netherlands

Although, in England, the transfer window formally opens on 1 July, transfers between clubs in the same league can take place as soon as the last competitive fixtures for the season have been played. However, many transfers will not be completed until 1 July because many players' contracts expire on 30 June. International transfers cannot be made until the window has opened on 1 July. Outside of the transfer window, a club may still sign players on an emergency basis, usually if they have no goalkeeper available. Special dispensation from their competition's governing body, for example the Premier League, is required. The transfer window restriction does not apply to clubs below Football Conference National level.

If the last day of a transfer window is on a weekend, the deadline can be extended to the following Monday at the request of those involved for business reasons.The first shift of the deadline since its inception took place in summer 2008, when the deadline was extended by 24 hours to fall on Monday 1 September at midnight.The transfer deadline in England was similarly extended to 5 pm 1 September 2009, due to the August Bank Holiday. The German football league announced an extension of the January 2009 deadline to 2 February.

Free agents can be signed by a club at any time during the season, if they had been released by their previous club before the end of the transfer window.A club can request to sign a player on emergency basis, e.g. if several goalkeepers are injured at the same time.Outside of the transfer window in England, once seven days have passed following the end of a transfer window, clubs from The Football League (Regulation 53.3.4) and (provided the player is not registered with a club from any league below The National League) The National League (Rule 6.6.4) can loan in players i) in the first half of the season, until 5.00pm on the fourth Thursday in November and ii) in the second half of the season, until 5.00pm on the fourth Thursday in March. An existing loan deal can be made permanent at any time outside the transfer window.

The day upon which a window closes is known as transfer deadline day, and is usually one of the busiest days of the window, generating a flurry of transfers, often because a number of interdependent transfers are completed resembling a housing chain, generating much media interest