Yes, but § 1.162-17 requires expenses to be submitted to the employer in a timely fashion, at or near the time of the expenditure or use (see reference to § 1.274-5). The question here is, “five months into 2020 we are trying to figure out how much the employee can expect the employer to pay in 2019 under an accountable plan.” It’s an interesting question: “My father owns half this office, can I claim exclusive use even if my S Corporation can’t pay him rent?”