Congress works best when there’s a deadline. And there’s an important deadline coming up. Many federal tax breaks end after this year: Lower income tax rates. Higher standard deductions and child credit. Larger estate and gift tax exemption. Alternative minimum tax easings. And much more.

Odds for a tax bill this year are quite good. But the process won’t be all smooth sailing. We’ll look at some of the key sticking points that Republican lawmakers will have to work through.

First is timing. Donald Trump and some GOPers want taxes passed quickly. They want tax changes in one early big bill that would also include border security and energy reform. Others desire a two-pronged plan: Address border and energy first, thinking that would be easier procedurally, and then turn to federal tax changes. On top of this, lawmakers will have to tackle government funding and the debt ceiling.
Second is the slim House GOP majority and less-than-60 Senate GOP majority. With a one- or two-person House majority, GOPers can’t afford to lose votes. A group of two or more naysayers can wield lots of power and affect what goes in or stays out of any tax bill. Also, Republicans will use budget reconciliation to override the need for 60 votes in the Senate to defeat a filibuster. This procedure has lots of arcane rules, which will make the nonpartisan Senate parliamentarian a key figure to watch.
Third is the cost. It’s estimated that extending the expiring tax provisions would add $4.6 trillion to the now $36 trillion federal debt. Not included in that cost are the other tax breaks that Trump promised various groups during his campaign.
Fourth is the issue of tariffs. Trump backs blanket tariffs on imported goods. The tariffs would raise revenue that could be used to help offset the cost of tax cuts, but they would also cause the prices of many everyday items to go up for consumers.
Fifth is Trump’s campaign vows for even more tax cuts above and beyond what is expiring in 2017’s Tax Cuts & Jobs Act. They include making tips, overtime pay and Social Security benefits tax-free; letting individuals deduct interest that they pay on loans to buy a car; and increasing the child tax credit amount. These extra easings would hike the cost of any tax bill, and there might not be enough GOP support.
Sixth is how to fix the state and local tax (SALT) deduction taken by itemizers on Schedule A. Currently, there is a $10,000 cap on this write-off. But House GOPers from some high-tax states want to hike the limit or repeal it. If nothing is done, the $10,000 cap disappears. Trump supported lifting the cap on the campaign trail, and he needs the votes of these Republicans from high-tax states to pass a tax bill. But increasing the cap or getting rid of it altogether would cost the government a lot of revenue that Trump and Congress would want to use for other tax cuts.