There are some fundings which support early-career researcher by letting him to work/visit another institute/university for few months. Those fundings normally pay for travel and accommodation expenses (not living expenses) and require a candidate to be affliated of one organisation, e.g. to be a post-doc.
My question is that if a researcher who wants to apply for those fundings should let his boss, whose funding is paying his salary, know before applying or after knowing that his application is successful.