When are you allowed to submit an IDS, and what must also be submitted?

There are three relevant periods to submit an IDS:

A. Within three months of filing the patent application, or before receiving a first office action on the merits -- you can submit your IDS without paying a fee, and without having to make the certification statement.

B. After the period A above,  but before prosecution has closed, and before you have received a final office action, and before you have received a notice of allowance --  you can submit your IDS, but you must either pay the fee, or you must make the required certification statement.

C. After the period B above, you must pay the fee and make the required certification statement.