You can only use the personal data for a new purpose if either this is;
- compatible with your original purpose.
- you get consent.
- you have a clear obligation or function set out in the law.
The following purposes should be considered to be "compatible" purposes:
- archiving purposes in the public interest;
- scientific or historical research purposes; and
- statistical purposes.
Otherwise, the GDPR says that to decide whether a new purpose is compatible (or as the GDPR says, “not incompatible”) with your original purpose you should take into account:
- any link between your original purpose and the new purpose;
- the context in which you originally collected the personal data – in particular, your relationship with the individual and what they would reasonably expect;
- the nature of the personal data – eg is it particularly sensitive;
- the possible consequences for individuals of the new processing;
- whether there are appropriate safeguards - eg encryption or pseudonymisation.
As a general rule, if the new purpose is either very different from the original purpose, would be unexpected, or would have an unjustified impact on the individual, it is likely to be incompatible with your original purpose. In practice, you are likely to need to ask for specific consent to use or disclose data for this type of purpose.
A carpenter discloses his customer information to his friend's decorating company for them to target with their services. Disclosing the information for this purpose would be incompatible with the purposes for which it was obtained. As there is no legal obligation to do this, consent would need to be gained from the individual.
If you wanted to analyse your customer's data for research and development purposes, you would need to gain their consent, unless you can pseudonymise the data before your process it for this purpose.
In the example of the carpenter and the decorator, pseudonymising the data before it was processed would mean you could carry out analytical processing on the data without seeking consent. This would mean the carpenter could share information about the target market demographics, without the need for consent so long as all personally identifiable information has been replaced with an unrelated pseudonym.
What the regulator says
1. Processing shall be lawful only if and to the extent that at least one of the following applies:
- (a) the data subject has given consent to the processing of his or her personal data for one or more specific purposes;
- (b) processing is necessary for the performance of a contract to which the data subject is party or in order to take steps at the request of the data subject prior to entering into a contract;
- (c) processing is necessary for compliance with a legal obligation to which the controller is subject;
- (d) processing is necessary in order to protect the vital interests of the data subject or of another natural person;
- (e) processing is necessary for the performance of a task carried out in the public interest or in the exercise of official authority vested in the controller;
- (f) processing is necessary for the purposes of the legitimate interests pursued by the controller or by a third party, except where such interests are overridden by the interests or fundamental rights and freedoms of the data subject which require protection of personal data, in particular where the data subject is a child.
Point (f) of the first subparagraph shall not apply to processing carried out by public authorities in the performance of their tasks.
2. Member States may maintain or introduce more specific provisions to adapt the application of the rules of this Regulation with regard to processing for compliance with points (c) and (e) of paragraph 1 by determining more precisely specific requirements for the processing and other measures to ensure lawful and fair processing including for other specific processing situations as provided for in Chapter IX.
3. The basis for the processing referred to in point (c) and (e) of paragraph 1 shall be laid down by:
- (a) Union law; or
- (b) Member State law to which the controller is subject.
The purpose of the processing shall be determined in that legal basis or, as regards the processing referred to in point (e) of paragraph 1, shall be necessary for the performance of a task carried out in the public interest or in the exercise of official authority vested in the controller. That legal basis may contain specific provisions to adapt the application of rules of this Regulation, inter alia: the general conditions governing the lawfulness of processing by the controller; the types of data which are subject to the processing; the data subjects concerned; the entities to, and the purposes for which, the personal data may be disclosed; the purpose limitation; storage periods; and processing operations and processing procedures, including measures to ensure lawful and fair processing such as those for other specific processing situations as provided for in Chapter IX. The Union or the Member State law shall meet an objective of public interest and be proportionate to the legitimate aim pursued.
4. Where the processing for a purpose other than that for which the personal data have been collected is not based on the data subject's consent or on a Union or Member State law which constitutes a necessary and proportionate measure in a democratic society to safeguard the objectives referred to in Article 23(1), the controller shall, in order to ascertain whether processing for another purpose is compatible with the purpose for which the personal data are initially collected, take into account, inter alia:
- (a) any link between the purposes for which the personal data have been collected and the purposes of the intended further processing;
- (b) the context in which the personal data have been collected, in particular regarding the relationship between data subjects and the controller;
- (c) the nature of the personal data, in particular whether special categories of personal data are processed, pursuant to Article 9, or whether personal data related to criminal convictions and offences are processed, pursuant to Article 10;
- (d) the possible consequences of the intended further processing for data subjects;
- (e) the existence of appropriate safeguards, which may include encryption or pseudonymisation.
- GDPR: Principles relating to the processing of personal data - Article 5 (1b)
- GDPR: Lawfulness of processing - Article 6
- GDPR: Processing of special categories of personal data - Article 9
- GDPR : Principles - Recitle 49
- GDPR : Principles - Recitle 450
- ICO - Purpose-limitation