After filing tax return - received additional tax documents

Basically, you will have to file an amended return (IRS Form 1040X)to include or exclude items of income or expenses that you didn’t include on the return already filed. If you know you are waiting for some information, do not file your return on 4/15/XX.) You are entitled to a six month extension to file(not to pay). Try to avoid filing amended returns. They are subject to additional scrutiny by the IRS.