There is no general size-based exclusion.
However, there are specific requirements regarding the duration of the probationary period which apply to undertakings with less than 20 employees. (see sec. 67A ERA inserted on 1 March 2009, by the Employment Relations Amendment Act 2008 (2008 No 106)).

See sec. 6(1) ERA: "Employee -
(a) means any person of any age employed by an employer to do any work for hire or reward under a contract of service; and (b) includes -
(i) a homeworker; or
(ii) a person intending to work; but
(c) excludes a volunteer who
(i) does not expect to be rewarded for work to be performed as a volunteer; and
(ii) receives no reward for work performed as a volunteer; and
(d) excludes, in relation to a film production, any of the following persons:
(i) a person engaged in film production work as an actor, voice-over actor, stand-in, body double, stunt performer, extra, singer, musician, dancer, or entertainer:
(ii) a person engaged in film production work in any other capacity.
(1A) However, subsection (1)(d) does not apply if the person is a party to, or covered by, a written employment agreement that provides that the person is an employee".
Note that the ERA applies in relation to the Public Service (art. 67 of the State Sector Act 1988, No. 20 of 1988 as amended up to Act No. 133 of 2010).

See sec. 66 ERA on fixed-term employment:
- According to 66 ERA, an employee and an employer may agree that the employment of the employee will end:
(a) at the close of a specified date or period; or
(b) on the occurrence of a specified event; or
(c) at the conclusion of a specified project.
However, according to the ERA, the employer must have genuine reasons based on reasonable grounds for resorting to fixed-term employment and must advise the employee of when or how his or her employment will end and provide the reasons justifying it.
- Sec. 66(3) ERA provides that the following reasons are not genuine reasons:
(a) to exclude or limit the rights of the employee under the ERA
(b) to establish the suitability of the employee for permanent employment:
(c) to exclude or limit the rights of an employee under the Holidays Act 2003.

No statutory limitations. However, the employer must have genuine reasons based on reasonable grounds for resorting to fixed-term (art. 66(2)a) ERA).

No statutory limitations. However, the employer must have genuine reasons based on reasonable grounds for resorting to fixed-term (art. 66(2)a) ERA).

Percentage of temporary workers, as of March 2008.
Note that temporary workers do not only cover fixed-term workers but also casual worker, temporary agency worker and seasonal worker.
Source: Survey of Working Life: March 2008 quarter - Hot Off the Press.
(Available at: http://www.stats.govt.nz/browse_for_stats/work_income_and_spending/employment_and_unemployment/SurveyOfWorkingLife_HOTPMar08qtr/Tables.aspx)

Sec. 67 ERA permits probationary employment but does not set out any maximum duration for it. The probationary period shall be established in writing in the employment agreement.
It is important to note that even during the probationary period, an employee is covered by the protection against unfair dismissal.
However, a new section 67A was inserted on 1 March 2009, by the Employment Relations Amendment Act 2008 (2008 No 106), according to which a probationary period of up to 90 calendar days can be stipulated in an employment agreement in writing if the employer employs fewer than 20 employees. During that period, the employer may dismiss the employee and if the employer does so, the employee is not entitled to bring a personal grievance or other legal proceedings in respect of the dismissal.
NEW: Following the entry into force of the Employment Relations Act Amendment No 125 of 2010 on 1 April 2011, this 90-day trial period is no longer limited to contract with employers having less than 20 employees, it has been extended to all employers.

See sec. 104 ERA prohibiting discrimination in employment which includes dismissal:
* on the prohibited grounds listed in sec. 105 ERA (sex, marital status, religious belief, ethical belief, colour, race, ethnic or national origins, disability, age, political opinion, employment status, family status, sexual orientation). Discrimination on such grounds is also prohibited under the Human Rights Act, 1993;
* on the grounds of involvement in the activities of a union. The statutory definition of involvement union activity includes trade union membership and also a number of grounds such as participation in a lawful strike, filing a complaint or participation in proceedings against an employer, submitting a personal grievance against an employer, taking an employment relations education leave or acting as a health and safety representative under the Health and Safety in Employment Act, 1992;(sec. 107 ERA)
* on grounds of pregnancy and of a woman's state of health during pregnancy, and on grounds that a male or female employee intends to take parental leave or to assume the care of a child with a view of adoption. Dismissal of employees is also prohibited during parental leave and during 26 weeks thereafter. The dismissal of a pregnant employee is permitted if her state of health is materially affected by causes which are not related to pregnancy (sec. 49 of the Parental Leave and Employment Protection Act 1987);
* based on the employee's refusal to perform work likely to cause serious harm (as provided in art 28A Health and Safety in Employment Act 1992).

As already stated, dismissal is prohibited on grounds of pregnancy and of a woman's state of health during pregnancy, and on grounds that a male or female employee intends to take parental leave or to assume the care of a child with a view of adoption. However, the employer is allowed to dismiss an employee for a substantial reason which is not related to the above-mentioned grounds.

There is a special protection against dismissal of a male or a female employee during parental leave and during 26 weeks thereafter: it is prohibited for the employer to dismiss them. However, this prohibition is not absolute: the dismissal will be lawful if the employer proves that he/she terminated the employee's employment on account of a redundancy situation of such nature that there was no prospect of the employer being able to appoint the employee to a position which was vacant and which was substantially similar to the position held by the employee at the beginning of the employee's parental leave.
(See sec. 49-52 of the Parental Leave and Employment Protection Act 1987)

The ERA does not require that the dismissal notification be in writing. The form of the notification can be specified in an employment contract.
However, any dismissed employee has the right to request a written statement indicating the reasons for the dismissal, within 60 days after the dismissal or within 60 days after the employee has become aware of the dismissal, whichever is the later. The employer shall provide such statement within 14 days after the request (art. 120 ERA).

No specific period of notice is required by statute. Notice requirement is a matter for contract. Where notice is specified under the contract of employment or under a collective agreement, failure to provide such notice will be treated as a factor evidencing an unjustified dismissal. Moreover, failure to give the requisite notice is also a breach of contract which is actionable by a claim for breach of contract or by arrears of wages claim. Where notice is not specified in the contract, the adjudicatory bodies will determine what constitutes reasonable notice in the circumstances.

No definition of collective dismissal.
However, there is a generally accepted definition of redundancy which is derived from the Labour Relations Act 1987, and was later endorsed by the Courts. Redundancy means "a situation where [a] worker's employment is terminated by the employer, the termination being attributable, wholly or mainly, to the fact that the position filled by that worker is, or will become, superfluous to the needs of the employer".
(see "Restructuring and redundancy", Report of the Public Advisory Group on restructuring and redundancy, June 2008, p. 9, available in pdf format under "Scope of additional information" bellow)

Consultations requirement in the event of a collective dismissal derives from sec. 4 of the ERA which provides for a duty of good faith in the employment relationship.
This duty of good faith, amongst other things, requires an employer who is proposing to make a decision that will, or is likely to, have an adverse effect on the continuation of employment of 1 or more of his or her employees to provide to the employees affected (and any relevant union representative):
i) access to information, relevant to the continuation of the employees' employment, about the decision; and
(ii) an opportunity to comment on the information to their employer before the decision is made."
Section 4(4) ERA makes it clear that the duty of good faith extends to:
- consultation (whether or not under a collective agreement) between an employer and its employees, including any union representing the employees, about the employees' collective employment interests, including the effect on employees of changes to the employer's business;
- a proposal by an employer that might impact on the employer's employees, including a proposal to contract out work otherwise done by the employees or to sell or transfer all or part of the employer's business;
- making employees redundant.

This duty of good faith, amongst other things, requires an employer who is proposing to make a decision that will, or is likely to, have an adverse effect on the continuation of employment of 1 or more of his or her employees to provide to the employees affected (and any relevant union representative):
i) access to information, relevant to the continuation of the employees' employment, about the decision; and
(ii) an opportunity to comment on the information to their employer before the decision is made."
Section 4(4) ERA makes it clear that the duty of good faith extends to:
- consultation (whether or not under a collective agreement) between an employer and its employees, including any union representing the employees, about the employees' collective employment interests, including the effect on employees of changes to the employer's business;
- a proposal by an employer that might impact on the employer's employees, including a proposal to contract out work otherwise done by the employees or to sell or transfer all or part of the employer's business;
- making employees redundant.

There are no statutory limitations as to the amount of compensation to be awarded in the event of unfair dismissal.
Sec. 123 ERA provides that if the Employment Authority or Court determines that a dismissal was unjustified, it may provide for any 1 or more of the following remedies:
- reinstatement;
- reimbursement of the whole or any part of the wages lost as a result of the dismissal;
- compensation for humiliation, loss of dignity, and injury to the feelings of the employee; and loss of any benefit, whether or not of a monetary kind, which the employee might reasonably have been expected to have obtained had he or she not been dismissed.
According to the OECD table on "Employment protection on New Zealand - 2008", the typical compensation awarded in the event of the unfair dismissal of an employee with 20 years of service is: "backpay of 6 months (assuming case takes 6 months) and median compensation payment of NZD 6 500 (equivalent to 1.7 months wages)".
(Available at: http://www.oecd.org/dataoecd/26/21/42746308.pdf)

NEW: The 2010 Employment Relations Amendment Act which entered into force on 1 April 2011 modified the provision on reinstatement. Sec 125 ERA (as amended) provides that if sought by the employee, the Authority may, whether or not it provides for any of the other remedies, provide for reinstatement if it is practicable and reasonable to do so. The law no longer requires reinstatement to be the primary remedy: the Authority is not anymore obliged to ("must") order reinstatement (unless it is not practicable to do so) if so requested by the employee.

- The Department of Labour provides a Mediation services in order to help the employer and employee to resolve their dispute by mutual agreement. If the parties come to an agreement, once it is signed by the Mediator, it will be final and binding.
- In addition, the ERA provides for the duty of the Employment Relations Authority to consider mediation (sec. 159 ERA). That means that it shall first consider whether an attempt has been made to resolve the matter by the use of mediation and must direct that mediation or further mediation be used before it investigates the matter, unless it considers that it would not contribute constructively to resolving the matter; or be in the public interest; or undermine the urgent or interim nature of the proceedings.

- The ERA gives exclusive jurisdiction to the Employment Relations Authority, an independent body, to make determination about personal grievances, which amongst other things include unfair dismissal claims (sec. 161(1)e) ERA). This provision removed the possibility for employees to pursue a claim for wrongful dismissal under civil law.
- Either the employer or employee may challenge a determination of the Authority, within 28 days after the date of the determination, in the Employment Court.
A challenge may relate to the whole of the determination (in which case, there will be a de novo hearing) or be restricted to some limited aspect of a determination (sec. 179 and 187 ERA)

The ERA reserves the possibility for the parties to resort to arbitration or other mediation services. (secs. 154 and 155 ERA)