Google-sheets – How to use a checkbox to choose to add the value or not in total

Please try, in B2 of Expense_Overview:

=sumif(Expense_Detail!D:D,A2,Expense_Detail!C:C)  

copied down to suit, or:

=ArrayFormula(sumif(Expense_Detail!D:D,A2:A,Expense_Detail!C:C))

You have a treat in store whenever you get around to pivot tables. They are very powerful but incredibly easy to use for all that:

Select A1:D7 in Expense_Detail, Data, Pivot table report..., for Rows Add field select Expense Category, for Values Add field select Amount.

PS Remove trailing space from A3 in Expense_Overview.

PPS If a pivot table will do the job it is normally far and away the best (and often easiest!) solution.

This can't be done via "standard" means. Formulas are not permitted as custom checked/unchecked values.

here is one of many methods of how to fake it:

• decide on cell height / width / color / background color
• insert checkbox
• zoom in via browser zoom CTRL + +
• take a screenshot (ticked and unticked)
• photoshop it (count for the frame around checkbox)
• upload it (preferably on your Google Drive to minimalize update lag response)
• and then use a simple IF statement to insert those images based on another checkbox

=IF(E23=1;   
    IMAGE("https://i.imgur.com/DgTwvYi.png");
    IMAGE("https://i.imgur.com/8AxCgKZ.png"))