For how long do I keep original invoices of my business?
If you have a business in Spain and wish to stop trading, keep an eye on your original invoices for at least 6 years!
The Spanish Tax Office has the right to review your tax forms for a long period of time and they are free to request original invoices for the costs deduced on your gains.
Besides this, I would also make sure you give to your accountant your contact numbers where he can contact you in the event you receive a notification from the Tax Office.
Nowadays, accountants submitt our tax forms by internet so tax inspectors have their contact details. They will contact them in the event do not reach you at your place!
If you plan to leave Spain for some time, make sure you have appointed your accountant as your tax representative in Spain and have granted power of attorney!