Please note that if your income document(s) show a different or old address, that is not a problem at all. The address on the form is most likely only used by your employer for their records.
Make sure to provide your current address on Step 2 Getting to know you, sub step Your address as that is the address that would appear on your tax returns and not the one from your income documents(s).
Important: Ensure that the address you provide on your tax return will be valid for at least few months in case the tax office sends you any correspondence.