Financial projections can be considered part of PM discussion in PM SE? I´m not sure if it is directly related to project or financial issues (there is another site that handles financial Q&A?).
I think that as long as the question is related to managing project finances/budgets then it should be okay. Money is a resource that needs to be managed and is often (always?) a constraint that needs to be considered in project management. Cost management is also one of the PMBOK knowledge areas. That said, if the question were about pure financial management (like, how should VAT be applied in a particular scenario) then it might veer off-topic.