SOSTAC is a marketing model developed by PR Smith in the 1990s  and later formalized in his 1998 book Marketing Communications, the subsequent series of SOSTAC Guides to your Perfect Plan (2011) and the SOSTAC Guide to your Perfect Digital Marketing Plan (2020). 
It is an acronym for Smith's six fundamental facets of marketing: situation, objectives, strategy, tactics, action and control.
SOSTAC contains a general marketing strategy which can be applied in various commercial situations. It includes an in-depth SWOT analysis, which helps businesses get ready for marketing campaigns; the main difference is that SOSTAC also focuses on the implementation stages of the process, on marketing communications  and now, digital marketing.
The structure of SOSTAC is a simple logic that builds on an in-depth Situation Analysis which informs subsequent decisions made about strategy and tactics. It is crystal clear logic enables better decision making and therefore better plans .
Marketing experts have adapted SOSTAC to a number of specific situations, including direct marketing and electronic marketing. The steps in the process have also been adapted to the development of internet security systems and company business plans.
Steps in SOSTAC
- Situation assesses where a business is presently (where are you now?).
- Objectives sets the mission or goals for the business (where do you want to be?).
- Strategy is an overview of how to achieve the objectives (how do you get there?).
- Tactics are the details of strategy (e.g. the marketing mix)
- Actions how do you ensure excellent execution of the plan.
- Control establishes how you know whether you are getting there (what do you monitor?).
- Smith, PR (1998). Marketing Communications - an integrated approach (2nd ed.). London: Kogan Page.
- Steve Bax; Paul Woodhouse (3 July 2013). Cambridge Marketing Handbook: Communications. Kogan Page. pp. 69–. ISBN 978-0-7494-7062-3.
- Ozuem, Wilson (2 February 2016). Competitive Social Media Marketing Strategies. IGI Global. pp. 5–. ISBN 978-1-4666-9777-5.
- Smith, PR (2011). SOSTAC Guide to writing the Perfect Marketing Plan. Amazon self-publishing.
- Smith, PR (2020). SOSTAC Guide to your Perfect Digital Marketing Plan. Amazon self-publishing.
- Chris Fill (2002). Marketing Communications: Contexts, Strategies, and Applications. Financial Time Prentice Hall. p. 301. ISBN 978-0-273-65500-8.
- Roddy Mullin (2002). Direct Marketing: A Step-by-step Guide to Effective Planning and Targeting. Kogan Page Publishers. pp. 40–. ISBN 978-0-7494-3677-3.
- "Planning For SEO Success In 2016". Search Engine Land, Marcus Miller, December 28, 2015
- John Hawkey (2002). Exit Strategy Planning: Grooming Your Business for Sale Or Succession. Gower Publishing, Ltd. pp. 74–. ISBN 978-0-566-08498-0.
- Joan Van Tassel (10 September 2012). Managing Electronic Media: Making, Moving and Marketing Digital Content. CRC Press. pp. 208–. ISBN 978-1-136-03162-5.
- Michael Baker; Susan Hart (10 September 2008). The Marketing Book. Routledge. pp. 507–. ISBN 978-1-136-35684-1.
- "How to Use SOSTAC to Build Your Security Strategy". Business2Community, by Venkat Pothamsetty May 1, 2016
- "How to assemble an effective digital marketing plan for your business". Business in Vancouver, May 12, 2015 Cyri Jones and Ivan Surjanovic
- Sascha Kurth (28 January 2011). Molson Coors to launch “clear beer for women”: Campaign Planning and Development Individual Assignment. GRIN Verlag. pp. 2–. ISBN 978-3-640-81303-2.