Is there an formula what gives me the first day of the next month after a DB-date?

In the Database is a datefield, i have to count a marge of 30 days with the formula dateadd(d, 30, {db-field})
After this function i need to calculate the next first day of the next month.

For example: DB-field = 24-04-2018
With a marge of 30 days gives me: 24-5-2018
And Now i need als result 1-6-2018.

A other example: DB-field = 05-11-2018
With a marge of 30 days gives me: 05-12-2018
And Now i need als result 1-1-2019.

I’ve tried the function dateserial() , but then i have a problem by passing a new year....
Who van help me?