$date + 1 year?

To add one year to todays date use the following:

$oneYearOn = date('Y-m-d',strtotime(date("Y-m-d", mktime()) . " + 365 day"));

For the other examples you must initialize $StartingDate with a timestamp value for example:

$StartingDate = mktime();  // todays date as a timestamp

Try this

$newEndingDate = date("Y-m-d", strtotime(date("Y-m-d", strtotime($StaringDate)) . " + 365 day"));

or

$newEndingDate = date("Y-m-d", strtotime(date("Y-m-d", strtotime($StaringDate)) . " + 1 year"));

Try: $futureDate=date('Y-m-d',strtotime('+1 year',$startDate));

If you are using PHP 5.3, it is because you need to set the default time zone:

date_default_timezone_set()

strtotime() is returning bool(false), because it can't parse the string '+one year' (it doesn't understand "one"). false is then being implicitly cast to the integer timestamp 0. It's a good idea to verify strtotime()'s output isn't bool(false) before you go shoving it in other functions.

From the docs:

Return Values

Returns a timestamp on success, FALSE otherwise. Previous to PHP 5.1.0, this function would return -1 on failure.

Try This

$nextyear  = date("M d,Y",mktime(0, 0, 0, date("m",strtotime($startDate)),   date("d",strtotime($startDate)),   date("Y",strtotime($startDate))+1));

My solution is: date('Y-m-d', time()-60*60*24*365);

You can make it more "readable" with defines:

define('ONE_SECOND', 1);
define('ONE_MINUTE', 60 * ONE_SECOND);
define('ONE_HOUR',   60 * ONE_MINUTE);
define('ONE_DAY',    24 * ONE_HOUR);
define('ONE_YEAR',  365 * ONE_DAY);

date('Y-m-d', time()-ONE_YEAR);

You can use strtotime() to get future time.

//strtotime('+1 day');
//strtotime('+1 week');
//strtotime('+1 month');

 $now = date('Y-m-d'); 
 $oneYearLaterFromNow = date('Y-m-d', strtotime('+1 year'));
 $oneYearLaterFromAnyDate = date('Y-m-d', strtotime('+1 year', strtotime($anyValidDateString)));