These two border crossings (open 24 hours) are the most common entry and exit points for the UAE. Wajaja is the post that buses use (it takes about an hour for a full bus to clear through immigration) while Khatmat Milahah is more useful for those with their own transport wanting to explore the eastern coast of the UAE. A good tip when using either border is to bring a photocopy of your passport and a pen – you may find that this helps speed up the process, which can be lengthy at weekends and on public holidays. You have to park before the border post and enter the arrivals hall to complete the formalities. The route to Dubai from Wajaja takes you in and out of Omani territory (the border is not a straight line) with checkpoints at each crossing but this usually involves a quick wave of your passport.
You can take a hire car across the border if you have insurance (available from booths at both crossings) but it is much quicker to clear immigration if you have arranged insurance in advance. Don't try to take beer in your coolbox in either direction. There's no exit tax for Oman; exit tax from UAE costs Dh36, payable only by credit card.
The rules regarding entry and exit formalities change frequently so check with the Royal Oman Police (www.rop.gov.om) before travelling.