Lula is facing five charges related to the Car Wash scandal, a three-year investigation that has embroiled more than 100 politicians.
If convicted, he could face jail. If he gets off, he could return to the presidency in the 2018 elections.
He denies any wrongdoing.
Lula will give his testimony at a court in the southern city of Curitiba, where hundreds of his red-shirted supporters have been gathering to protest.
It’s been a rough week for Lula; yesterday a judge shut down the Lula Institute:
A Brazilian judge ordered on Tuesday that the institute founded by former President Luiz Inacio Lula da Silva suspend its operations.
The ruling was made by federal Judge Ricardo Augusto Soares Leite, who is overseeing one of the five prosecutions Lula faces for alleged corruption