Transferring money between budgets or envelopes allows you to re-allocate funds from an over-performing budget to an under-performing one, covering the deficit. This is useful, for example, if it's end of the month and your Entertainment budget still has some money left. Instead of looking for a way to quickly spend that money, you could re-allocate it to your Emergency Fund for example.
To create a budget transfer, click on the + button at the bottom of the budget screen (while viewing a budget you want to make the transfer from) and select "Budget transfer" from the tabs on top. You'll be asked to provide:
From and To Budget: if needed, you can change where the transfer will draw from and where it'll arrive.
Transfer amount: how much money to transfer from one budget to another.
Description: the text to go with the transfer.
Date and time: the date and time of the transaction.
Budget transfers work differently depending on whether the source/target budget is an expense or income budget:
if you transfer money from an expense budget to an expense budget, MoneyWiz will adjust the "Budgeted" amount of each,
if you transfer money from an expense budget to an income budget, MoneyWiz will reduce the "Budgeted" amount in expense budget and increase "Saved" amount in income budget,
if you transfer money from an income budget to an expense budget, MoneyWiz will reduce the "Saved" amount in income budget and increase "Budgeted" amount in expense budget,
if you transfer money from an income budget to an income budget, MoneyWiz will adjust the "Saved" amount of each.
"Saved" amount in income budgets represents the money that is immediately available to spend. "Budgeted" amount in expense budgets represents the same kind of money, therefore the logic described above allows you to transfer available funds among budgets of different nature.