Your design looks pretty good overall, but here are a couple of things to check:
Using Person_ID as the primary key is spot on. The Company_ID as a foreign key makes sense too, since each person is linked to a company. Company Table:
Company_ID is correctly set as the primary key. However, the Invoice_ID being in the Company table is a bit unusual unless each company only gets one invoice. If it’s a one-to-one relationship, that’s fine, but if companies can have multiple invoices, you might want to move the Invoice_ID to the Invoice table itself. Invoice Table:
The Invoice_ID as the primary key is good, and the Summary_ID and Detailed_ID as foreign keys make sense. Just a thought, though: since the invoice is broken into sections, you might want to make sure these two foreign keys are indeed related directly to the invoice. If you’re thinking of splitting the sections out to their own tables, that could change the structure a little. Summary and Detailed Tables:
Summary_ID and Detailed_ID are fine as primary keys. Linking Detailed_ID to Person_ID makes sense, since the detailed section includes individual person details.
Your foreign keys look solid. Just make sure that if each company has multiple invoices, you’ll need to adjust the design a bit to reflect that properly (maybe move the foreign key to the Invoice table). If it’s only one invoice per company, you’re good to go.
Also, consider adding cascading rules for deletes/updates to maintain data integrity in case a record is removed or changed.
Otherwise, everything looks pretty fine from my point of view.