Some EU countries implement rules where a non-Eu business would be required to appoint a Fiscal Representative when registering for VAT who is usually jointly and severally liable for the VAT owed. Germany however do not require this rule for non-EU companies and businesses can therefore register directly with their corresponding tax office in Germany without the need to appoint a local representative.
Businesses still may want to appoint an agent for registration and filing in Germany due to the complex registration process and tax laws only available in the local language.
Importing into Germany
European customs law in general does not allow import declarations by companies who are not resident within the EU. This means they will need to appoint a representative for declaring the imports into Germany. Instead of fiscal representation this is usually referred to as an Indirect Representative which fills a similar role.
Using DDP incoterms usually means the non-EU seller must VAT register in Germany and charge German VAT on the goods sold to the German consumer.