Initial Balance

You can set the 'Initial Balance' (sometimes referred to as a starting or opening balance) when creating an account. This can also be altered at any time.

Open the register of your account by clicking on it in the left sidebar, and then navigate to Account --> Edit Account from the Moneydance menu bar.

In the window that opens, you'll see the 'Initial Balance' field.
In this field you should enter the balance of your account, just before the earliest transaction in Moneydance.

For example, if the earliest transaction in your Moneydance account register is 1st January 2021, the initial balance amount is your bank account balance on 31st December 2020.

Moneydance can also calculate your Initial Balance.

For example, if your current checking account balance is $200, and the balance shown in Moneydance is $27.65, you can enter 200-27.65 (use the minus sign) in the Initial Balance field and hit enter.
Moneydance will automatically calculate the proper Initial Balance.