The FCDO position, stated plainly
In federal Iraq, the FCDO advises against all travel to the parts of Anbar province west of, but not including, Ramadi City; Diyala province except Baqubah City; Kirkuk, Ninawa and Salah al-Din provinces; Jurf al-Sakr town in Babil province; Sadr City in Baghdad province; within 5km of areas that border Iran in Wasit, Maysan and Basra provinces; and within 5km of Iraq's borders with Saudi Arabia and Kuwait.
It advises against all but essential travel to the remainder of Al-Muthanna, Al-Qadasiyah, Anbar, Babil (except Jurf al-Sakr), Baghdad (except Sadr City), Basra, Dhi Qar, Karbala, Maysan, Najaf and Wasit provinces, to Baqubah City, to sections of Highway 34 and Highway 2, and to the Kurdistan Region of Iraq. The FCDO says consular support is severely limited in areas it advises against, and that travel insurance could be invalidated if you travel against its advice.
Entry rules
For readers who have to explain the rules, the FCDO says your passport must have an expiry date at least six months after you arrive and at least one blank page, and that you must have a visa. You can no longer get a visit visa on arrival in federal Iraq and must apply on the Government of Iraq e-visa portal at least 24 hours before you travel. The visa costs 160 US dollars and is valid for 60 days, and you should hold a return ticket or a ticket onward to a third destination.
The Kurdistan Region has its own e-visa process, and it is also possible to get a visa on arrival there, but both types are valid for travel in the Kurdistan Region only. Weapon Authority Cards are required if you carry weapons, and foreign nationals have been arrested for failing to provide the correct documents.
Read the full Iraq guide on Visit Travel Group, or see VisitIraq.co.uk on Visit Travel Group.