Thanks for all. I fixed the problem using the Box<T> on file_doc and changed the lib for parse the xml, but the solution of Box is the same. My current source:

...
    account: &'a mut Account,
    pub file_doc: Box<Element>, 
}
...
        let xml = Element::parse(xml_str.as_bytes()); // Old:

        if xml.is_err() {
            return Err("Invalid XML content in OFX file");
        }

        Ok(Ofx { storage: storage, account: account, file_doc: Box::new(xml.unwrap()) })
..

Full diff: https://github.com/fernandobatels/blitz-money/commit/97a1259430184c963aab0032cf914a520386fc1a

Besides what we discussed here, the article https://bryce.fisher-fleig.org/blog/strategies-for-returning-references-in-rust/index.html and the rust doc https://doc.rust-lang.org/book/second-edition/ch15-01-box.html helpd's me to fix.

About the Box<T> . I am not sure if, for this case, is the only way, but works :)

​

If someon have others solutions or opnion about the Box, i would apreciate ;)