Money for iPhone has bi-weekly (and other custom) periodicity for planned transactions and budget.

When you add a planned transaction or budget record, tap “Peridiocity” cell, turn on “Custom” field, choose periodicity filter (e.g. Week) and set its quantity character (e.g. 2). This way you will get the following formula:

2 x Weekly

will result in bi-weekly periodicity.

Similarly 3 x Month will give us periodicity “once in 3 months” or “every quarter”. In this case, for planned transactions, the transaction will occur once in a quarter; while in the Budget this amount will apply for the whole quarter entirely.

Please note that in the case of weekly periodicity you cannot set a custom day when your week starts. The way how your week starts (i.e. on Monday or on Sunday) depends on your regional settings and is loaded from your iPhone settings.