comma after a clause acting as subject

Do not use a comma after a clause acting as a subject:

• Incorrect: Whatever you decide, is fine with me.
  Correct: Whatever you decide is fine with me.

In the example above, the noun clause Whatever you decide is the subject of the verb is. We don’t normally separate a subject from its verb with a single comma, even when the subject is an entire clause.

The one exception to this rule occurs when the verb at the end of the noun clause is the same as the verb in the main clause:

• What the cause of the leak is, is a total mystery.
• Whatever money Ray still had, had been invested.

In sentences like these, it is usual to use a comma for clarity.