Every complete sentence has a subject and predicate. We have used the term subject many times, but you may not be familiar with the term predicate. Basically, the predicate is the main verb in the sentence and everything that modifies or extends it. Consider this sentence.
“The man with the broken nose stumbled on the broken flagstone.”
The simple subject is “man,” and the entire subject of the sentence is “The man with the broken nose.” The main verb is “stumbled,” and the predicate is “stumbled on the broken flagstone.”
According to this tip, you should not place a comma between the subject and predicate. While this seems pretty obvious with the simple sentence above, I see many clients put a comma there when the subject is complicated. Consider this sentence.
“When the following morning finally arrived, the president of the bank that collapsed when the stock market tumbled was found dead.”
Here, the subject ends with “stock market tumbled,” and the predicate is “was found dead.” Due to the complexity of the subject, with its multiple phrases and clauses, some writers will put a comma after “tumbled.” Regardless of the sentence’s complexity, however, no comma is needed there.