As you needed to complete forms when you left, you
will need to fill in forms when you return. The easiest
way is to contact the consulate where you are registered
to sort out your situation. You will have to establish
a fully detailed inventory
of your furniture. A moving form attestation
is often demanded when you pass the border (you can
ask for it at your Consulate).
You will have to think about school registration if
you have children.
You need to inform your tax office of the changes and
fill a “déclaration provisoire et
anticipée des revenus” (provisional and anticipated
income declaration). The tax is immediately established
and payable. The tax office will give you then a “Quitus
fiscal”, evidence of the tax settlement, and
which might be ask by the customs when you move abroad.
Whatever the situation, we strongly advise you to go
to your tax office and ask for details.