Director’s remuneration for a non-profit organisation + self-employed main occupation

You mean to include that income as a director in your calculation of the impact on your personal income tax?

So that Dexxter, when we estimate your personal income tax, takes that income as a director into account? You can do this via 'Settings' (at the bottom of the left-hand side menu) and then click on 'Calculations'. There you can fill in an income, which Dexxter will take into account.

Please note that this only applies to personal income tax.

In your specifically case, that is not the only thing. You also have to pay social security contributions (I think) on that income as a director of the non-profit organisation. You will not be able to enter that correctly in Dexxter, so you will have to keep track of that yourself :)