Interior designs comes under

In case of initial expenditure, you may capitalize the same to the cost of the building else have an account as it is i.e interior design expenses under Indirect expenses.

But  you said Its new  LLP , expense may also be capitalize with cost  of Building . just  confirm with others also .

You can book it as fixed assets - Under Leasehold property improvement If rented office or you can take into furniture and fixtures account head.   

If it's for home then you should try Animal Skulls for decoration.

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