The Internal Revenue Services offices in Washington, D.C. Adam Jeffery | CNBC

If you haven't pulled your tax return together and sent it into the IRS by now, you're just about out of time. Monday, April 15, is Tax Day for most Americans. Due to Patriots' Day holidays on Monday in Maine or Massachusetts, taxpayers in those states have until midnight Wednesday to file. Procrastinators can request a six-month extension to submit their returns, but you only have until midnight Monday to submit taxes owed. The IRS is expecting to receive about 153 million individual tax returns from 2018 over the course of this year. This season is the first time taxpayers will file under the Tax Cuts and Jobs Act. This overhaul of the tax code roughly doubled the standard deduction to $12,000 for singles ($24,000 for married-filing-jointly), eliminated personal exemptions and limited itemized deductions.

Those changes threw taxpayers and accountants for a loop. The more elaborate the return, the longer people waited to submit their paperwork. "In terms of the tax season, this year was one of the worst with the slowness," said Jeffrey A. Porter, CPA and founder of Porter & Associates in Huntington, West Virginia. "We're going to have more extensions than we had in the past," he said. Here's what you should know in the final hours of tax season.

Get your paperwork

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Whether you have a last-minute appointment with your CPA or you have a date with your own tax prep software, you're going to have a rough time without the right forms and receipts. See below for CNBC's suggestions to help you gather what you need: ﻿Six tax breaks you'll lose on your 2018 return: Did you write-off a massive property tax bill last year? Maybe you had some property losses you were hoping to deduct. Here's the bad news: A number of itemized deductions are now out of reach. Save thousands with these credits and deductions your 2018 tax return: Not all deductions are out the window. Here are some valuable opportunities to save on your taxes. Prevent tax return anxiety by following these steps: Need a rundown of the changes to the new tax law and what they mean for your return? Find them here.

Refund or taxes owed?

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Prep for next year