From Longman Dictionary of Contemporary Englishfall behind (somebody/something) phrasal verb1 SLOWto go more slowly than other people so that they gradually move further ahead of you His mother was chatting and didn’t notice that he had fallen behind. She hurt her ankle and had fallen behind the others.2 EFFECTIVEto become less successful than other people, companies, countries etc After her time in hospital, Jenny’s parents are afraid she has fallen behind educationally. Companies that are not market-driven risk falling behind the competition.3 LATEto fail to finish a piece of work or pay someone money that you owe them at the right time with/on After losing his job, he fell behind with his mortgage payments. The project has fallen behind schedule. → fall→ See Verb table
Examples from the Corpus
fall behind • As before, they again fall behind early, but this time they battle back.• The level of provisions could begin to drop next year as fewer families fall behind in their home loan payments.• It seems that they are still working on how to use their time and some students are falling behind in their work.• Certain other students simply fell behind so much that they could not catch up later on.• In recent years, teachers' salaries have fallen behind those of other non-manual workers.• They had fallen behind to a crazy goal after 33 minutes.fallen behind schedule• Home project had fallen behind schedule.• Countless advanced communications projects have fallen behind schedule after being heavily promoted.• It seems that matters have fallen behind schedule and need to be put back on the rails.From Longman Business Dictionaryfall behind phrasal verbCOMMERCE1[intransitive, transitive] fall behind somebody/something to make less progress than others in a competitive situationSmall firms that fall behind technologically can be rapidly wiped out.2[intransitive] to fail to make payments on time, for example for rent or on a loan with/onHe had fallen behind with his mortgage after losing his job.3[intransitive, transitive] fall behind something to fail to finish work on timeContractors who fall behind schedule incur financial penalties. → fall→ See Verb table 