What are the fines for building illegally in Israel?

"Illegal building" can cover a number of things besides for just building a house without a permit. Here are a few more things included:

1. Making use of a property for a use otherwise than what the permit allowed. e.g. using a storage unit as a residential unit, an office space for a residential, etc.
2. Taking a property and dividing it into more housing units without a permit
3. adding additions to a structure without a permit

In all cases of Illegal building it's important to further determine how the action you took conforms to the Plans תכנית that apply to the location. 

For example, if the תכנית allows in your location for both מגורים and משרדים -- and you just simply only got a permit for מגורים -- then it's relatively simple to fix the problem. you'll just need to apply for a permit for משרדים. Seeing how it conforms to the תכנית you can assume you'll get it.

On the other hand, if what you did not only had no permit but also runs against the תכנית itself  -- then you're looking at much heftier consequences including destroying whatever you did and restoring the situation to as it was. Unless you can create a new תכנית that would conform to the municipalities vision and would validate the areas that you have currently as illegal. (this last option is what's known as a תכנית הכשרה).

With that having been said, let's now discuss what can happen if you build or own (yes, this includes if you unwittingly bought a property from someone who built something illegally and then sold it to you - yikes!) "Illegal Building" a.k.a בנייה בלתי חוקית in Israel.

October 25, 2017 is the day that everything changed in Israel with amendment 116 coming into effect (תיקון 116 לחוק התכנון והבניה). The amendment made sweeping changes to פרק י of the law regarding Penalties  - ענישה, and below i'll try to list some of them.  

The fundamental change of תיקון 116  was that it converted illegal building from being a solely "criminal" offense - עבירה פלילית, into being a municipal offense - עבירה מינהלית as well. While that might not sound  like much of a stringency, in reality it made the penalties a lot more severe.

Why is that?

What was happening in Israel until then was that people were building illegally and municipalities were required to take them to court before any action could really be done to them. This process was so long and laborious that municipalities often just gave up rather then pursue it.

Comes תיקון 116 and creates in 2017 a whole new approach to penalties which  includes the following:

• expanded authority of צווים מינהליים - i don't know what the english equivalent of צווים are, maybe "warrants", but essentially the municipality (without turning to the courts, much like parking tickets) can demand and command you to stop the building, evacuate it, stop using it, or in the most extreme case - destroy it.
• but wait, it gets better :) Then come the Municipal Fines. There was created a "Schedule of Fines" in the by-laws תקנות העבירות המינהליות as follows (dependent on Square Meters built illegally):

• For using an illegal building
• 25 - 100 sqm = 50K shekel
• >100 sqm = 100K shekel

• For building illegally 
• 25 - 50 sqm = 25K shekel
• 50 - 75 sqm =  50K shekel
• 75 - 100 sqm = 100K shekel
• <100 sqm = 150K shekel

If after all that you're still not deterred, then the Municipality can take you to court where you can face the following punishments:

• prison (1-2 years) (see further סעיפים 243-244 לחוק התכנון והבניה)
• For building a structure illegally you can be fined up to double the value of the land with the structure were it to have been permitted (סעיף 245.2)
• For making use of an illegal structure you can be fined up to double the difference in value of the land, between the usage that you did illegally versus the usage that was permitted. (סעיף 245.3)