What happens if the reference date is earlier than the rule's own start date?

The search effectively begins at whichever of the two dates is later, since an occurrence can never exist before the rule itself starts.

Can this find the next occurrence of a monthly or annual rule too?

Yes, it supports the same recurrence shapes as the Recurring Date Generator, including monthly and annual rules, not only weekly ones.

Next Occurrence Calculator

Pick a rule and a reference date. Find the next occurrence strictly after that reference date, not on it.

Worked example

A weekly Monday rule starting January 1, 2027, a Friday, checked against a reference date of January 1 itself, finds January 4 as the next occurrence, the first real Monday the rule actually generates on or after the rule's own start date. Move the reference date forward to January 4 itself, the exact day the rule lands on, and the next occurrence jumps to January 11 instead, a full week later, since the search always looks strictly after the reference date rather than treating a matching reference date as its own answer. That strictly-after behavior is deliberate. A "next" occurrence that could equal the date you are already standing on would not actually tell you anything new.

Common mistakes

Expecting the reference date itself to count as the next occurrence when it happens to match the rule. It never does. The answer is always strictly after the reference date, never equal to it.
Setting a reference date far outside the rule's own supported search horizon, which can leave no occurrence to find within the bounded window.

Limitations

The search for a next occurrence is bounded to a 5-year horizon from the rule's own start date, which keeps the underlying search fast and finite for any supported recurrence shape.

Frequently asked questions

What happens if the reference date is earlier than the rule's own start date?: The search effectively begins at whichever of the two dates is later, since an occurrence can never exist before the rule itself starts.
Can this find the next occurrence of a monthly or annual rule too?: Yes, it supports the same recurrence shapes as the Recurring Date Generator, including monthly and annual rules, not only weekly ones.