If you need to generate a dynamic series of dates with a formula that increase by one month from a single start date, you can do so with a formula that uses the DAY, MONTH, YEAR, and DATE functions.
How the formula works
In the example, B6 is the hard-coded start date and the formula in B7 is:
To solve this formula, Excel first extracts the year, month, and day values from the date in B6, then adds 1 to the month value. Next, a new date is reassembled by the DATE function, using the same day and year, and month + 1 for month.
The first formula therefore returns a new date of 10/28/2018, one month later than the starting date.
Once the first formula is entered, it is copied down as far as needed. Each subsequent formula creates a new date incremented by one day.
Note: if you start with a date like January 31, the formula above will skip February and move on to March. This happens because the new date, 2/31/2018 doesn’t exist, so Excel uses the day value to roll forward to 3/3/2018, 3 days after the last day in February.
If you need a series of dates where every date is the last day of the month you can use EODATE like this: