Calculate Date with other Date Field

I have an Form with an 2 Date Fields. 

Example:

I want to calculate some things:

1. end of year from date "Project Start" (31.12.xxxx) as a date value to calculate more
2. condition for: "Project End" can not be greater than year end of "Project Start" + 2 years

Example:
Project Start: 31.10.2018 --> to calculate "31.12.2018"

to calculate: "01.01.2019" and "31.12.2019"

Project End: 30.08.2020 --> to calculate "01.01.2020"

I need the values to calculate all quarter from every year between "Project Start" and "Project End"

Everything I've tested so far does not work, because the form does not load or the control shows #value.