For auto-synced wallets, Koinly carries out a comparison of your balances on Koinly against the balances on your exchange.
Why does the balance on Koinly not match my actual balance?
The balances on Koinly are calculated using the imported transactions so unless some transactions are missing on Koinly the balance should always match what you have on your exchange. This is a good way to determine whether or not all your transactions have been imported correctly.
If an issue is found you will notice a yellow warning next to the wallet as seen below (only for auto-synced wallets):
Clicking on the warning icon will show the difference between Koinly's balance and the balance reported by the exchange:
Difference = Koinly Balance - API Balance
If the difference is positive, it means the balance on Koinly is higher than your actual balance. This could mean that a withdrawal or a sell of that coin is missing.
A negative balance means the opposite. Perhaps a deposit or a purchase is missing.
If the differences are quite small ex. 0.001 then you can usually ignore them as they are caused by rounding precision. Larger differences may require more attention though.
The balance on Koinly is the same as my exchange but this warning is still there...
This warning is only updated after a sync has been completed, so it will disappear the next time the wallet is synced (in most cases). Note that for Ethereum wallets you may continue to see this warning even after a re-sync, this usually happens for coins that have undergone a token/address swap. Just make sure your balance on Koinly is correct and ignore the warning if it is.