Disambiguation & Labeling :
Preliminary vs simulated : you should try to be specific about the process in which this calculation is taking place; using "preliminary" suggests it is part of staged process. "simulated" on the other hand suggests a modeling activity where users could play around with the figures before committing. These considerations need to be taken into account when labeling which (in my opinion) is a substantial part of the solution in this case.
CTA: Commit to this calculation
This is another labelling issue : Poorly devised labels usually end up suffering from being ambiguous, overlong, complex, superfluous, so try to use labels that are descriptive but short. The button text "Commit to this calculation" suggest that you need to provide the user with more explanation about the process before guiding them to take action.
Progress bar and Endowed Progress Effect:
A progress bar is definitely a good idea, besides providing the user with information about the number of steps within the application process it has the advantage of making users feel they have made progress towards a a final goal (Endowed Progress Effect). This article from Smashing Magazine has great examples of progress bars adaptable for different contexts.
Facilitating the process:
Also consider revealing more information about the next step (if required)* (Information about step 2 in step 1, information about step 3 in step 2) This is particularly useful if users need to input details from official documents such as national insurance numbers, passports etc.This could potentially help you indicate the process is not yet finished!
*A simple tagline that will fit-in easily within a staged disclosure process.
This concept is simply to complex to encapsulate into iconic form "dashed lines" and if the the application process has multiple steps than there is no need to futher emphasis that the figures provided are binding. Users will expect the process to be finalised when they reach the last step in the process, at that point provide the user with clear and concise information about the implications of completing the process (next steps).
Also adapt your CTA labeling by using real world terminology: Apply, submit, signup, or any other term/verb that users would have used if they made the application offline.
Below is an excerpt from Windows User Experience Interaction Guidelines that i think is useful.
When users are committing to a task, use a commit button that is a
specific response to the main instruction (for example, Print,
Connect, or Start). Don't use generic labels like Next (which doesn't
imply commitment) or Finish (which isn't specific) for committing a
task. The labels on these commit buttons should make sense on their
own. Always start commit button labels with a verb.