Can I make multiple deposits to my savings account?

There are no limits to the number of deposits you can make for the Sparkonto Flex.

For Sparkonto Fast you can only make one deposit on each account. If you wish to deposit more money, you can open several Sparkonto Fast accounts with the same maturity. If you try to deposit more money into the same account, your money will instead be transferred to your Flex Savings Account or to the withdrawal account you have chosen in advance.