Can I omit helping verb in if...construction?

[dippradhan]

"BP should pay the fine today if they have not already".-- is this a correct construction? (source: my own sentence)
When do we need to repeat the action verb in the if clause?
Can we ignore the action verb sometimes?

Thanks for your help,
~Dipankar

[tim]

if it is clear what verb is omitted, you can omit the verb in a case such as this. your construction is fine..