Why Your 2026 Marketing Plan Should Start by Challenging Assumptions

Admission: I love iteration, optimization, and making continuous improvement.

However, I also love ROI. And, that means that sometimes I have to get out of my own way, apply different processes, and make room for the possibility of uncomfortable levels of change and challenges to plans and thinking.

So, with that honest truth out of the way, let’s dig in knowing that I’m sharing this article with you while also giving myself a personal challenge to make sure I’m putting my own advice into action as well.

I have found that most marketing teams begin annual planning by mapping out goals, tactics, and campaigns for the year ahead. It is a natural starting point. It feels productive and gives everyone a sense of forward momentum. (All good things!)

But in many cases, this start is already too far ahead. Before choosing tactics or even refining strategy, there is a more foundational step that usually gets skipped. Teams need to step back and acknowledge the assumptions they are already making about the coming year, and then challenge those assumptions before they shape the plan.

Assumptions are unavoidable. Every belief a team holds about budgets, traffic, conversion rates, resources, demand, visibility, internal alignment, competitive pressure, and timing is an assumption. Many of these assumptions operate quietly in the background. When they go unspoken and unchallenged, they become the hidden risks that cause even strong plans to break down.

A successful 2026 plan requires clarity. That clarity begins with identifying what you believe to be true, what you are guessing about, and what you expect from the market and your organization. Once assumptions are made visible, they can be tested, revised, monitored, or removed entirely. When they stay hidden, they undermine the accuracy and stability of the plan before the year even begins.

The Assumptions Shaping Plans That Slip Through

Before any tactic or goal is selected, there are always assumptions at play. They include beliefs about:

• Audience behavior and demand
• Channel performance and trends
• Competitor visibility and investment
• Internal capacity and execution speed
• The time it takes for content or SEO to generate results
• Sales readiness and follow up
• Website stability and development availability
• Budget consistency
• Leadership alignment and priorities

These assumptions are often not written down, yet they define expectations throughout the entire planning process. They influence what teams think is possible, how fast they believe results will come, how they assign resources, and how they communicate expectations to leadership.

When assumptions remain unacknowledged, planning becomes a series of optimistic guesses. Teams build forecasts (even with great data and insights) on top of beliefs that may not be accurate. They choose tactics that depend on conditions that may not exist. They create calendars with expectations that may not hold. The plan looks solid on paper, but it is built on a foundation that has not been tested or challenged.

Assumptions in themselves are not the problem. The real risk is ignoring them (or, making assumptions about assumptions…yes, I know this is getting a little circular, sorry).

Why Plans Fail When Assumptions Go Unchallenged

A plan does not fall apart because one tactic underperforms. It also doesn’t fail because of a strategy that is a little off. It falls apart because the environment the plan assumed it would operate within turns out to be different. Many marketing challenges in Q1 and Q2 come from mismatches between assumptions and reality.

If a plan assumes SEO will grow at the same pace as last year, it may overlook the impact of AI driven answers in LLMs or within search results pages. If a plan assumes budgets will hold steady, it may be blindsided by a midyear adjustment. If a plan assumes the team has the capacity to execute a large volume of work, it may collapse under operational constraints. If a plan assumes the website is stable, it may be caught when platform or development issues slow campaigns. If a plan assumes sales will respond consistently, it may misinterpret performance signals. I’ll stop here, you get the picture.

These challenges are not failures in execution. They are connected to failures to test assumptions before or while building the plan.

Once assumptions are made visible, they can be evaluated. When they are hidden, they act as silent risks that surface only when something breaks. A plan built on assumptions that have not been challenged is not a plan. It is a hope.

How to Build a 2026 Plan That Begins With Challenging Assumptions

Here are the steps to integrate assumption awareness into your planning process and strengthen every part of your 2026 plan.

1. Identify the assumptions behind every strategic decision

As you define strategic priorities, pause and ask what beliefs must be true for those choices to work. Look for assumptions about demand, timing, channel viability, resources, internal alignment, and capacity. Writing these down forces clarity and exposes blind spots early.

2. Challenge each assumption before accepting it

Ask whether the assumption is supported by data, recent behavior, or current conditions. Many assumptions are holdovers from past years that no longer apply. Some are based on optimism (or, pessimism) rather than evidence. Challenging them helps determine whether they should shape your plan or be reconsidered entirely.

3. Validate assumptions with data and stakeholder alignment

Assumptions about performance can be tested against analytics. Assumptions about capacity require input from the team. Assumptions about follow up require alignment with sales. Assumptions about timing should be compared to real production cycles. This step clears up misunderstandings and prevents surprises once execution begins. Without mind readers on your team, you’ll need to work through a process of surfacing and understanding any and all assumptions from stakeholders.

4. Decide which assumptions need monitoring throughout the year

Some assumptions will remain uncertain even after validation. We can’t fully remove them and it is healthy to incorporate them when they are named and known. These should become part of your ongoing review cadence so the team can revisit them as conditions change. This creates a natural bridge between the Strategy phase of START and the Review and Transformation phases planning work that keep the plan aligned during the implementation.

5. Use the refined assumptions to shape tactics and expectations

Once assumptions have been acknowledged, challenged, and validated, you gain a more stable foundation for planning. Tactics, timelines, and forecasts become more realistic. The plan becomes grounded in the conditions that are likely to hold true rather than in those that were never questioned.

6. Revisit assumptions as the year unfolds

Assumptions should not be documented once and forgotten. They should be part of regular planning checkpoints. When assumptions shift, the plan should adapt. This is where your planning work prevents drift and keeps strategy connected to reality throughout the year.

Final Thought

A strong 2026 marketing plan does not begin with tactics or timelines. It begins with acknowledging the assumptions your team is already making and challenging them before they take root. This step is often skipped because it seems intangible, but it is one of the most important parts of strategic planning. Assumptions influence everything. When they remain hidden, they weaken the foundation of the entire plan. When they are surfaced, examined, and validated, they become a tool that strengthens clarity, alignment, and decision-making.

The START Planning Process was created to bring structure, objectivity, and predictability to digital marketing. Challenging assumptions supports that effort by grounding your plan in what is real rather than what is assumed. It makes strategies more stable, execution more focused, and course corrections more intentional. If you want your 2026 plan to stay aligned and effective, begin by taking a step back and questioning what you believe to be true.