As of 2021, the Illinois-Missouri reciprocity agreement is still in effect, allowing residents of Illinois and Missouri to work in either state without having to pay income taxes to both.

The agreement was first established in 2002 and has been renewed multiple times since then. It applies to all income earned in either state, including wages, salaries, commissions, and tips.

Residents of either state who work in the other state must file a non-resident tax return with that state, but they will only be taxed on income earned in that state. This means that if you live in Illinois but work in Missouri, you will only have to pay Missouri income taxes on the income you earn in Missouri.

Similarly, if you live in Missouri but work in Illinois, you will only have to pay Illinois income taxes on the income you earn in Illinois.

The reciprocity agreement is designed to make it easier for people who live near the border between Illinois and Missouri to work in either state without having to worry about double taxation. It also makes it easier for employers who have employees who work in both states to handle their payroll.

However, it`s important to note that the reciprocity agreement only applies to income taxes. Residents of either state will still have to pay other taxes, such as property taxes and sales taxes, to their respective states.

It`s also worth noting that the Illinois-Missouri reciprocity agreement is not unique. Many states have similar agreements with their neighboring states to make it easier for residents to work across state lines.

In conclusion, the Illinois-Missouri reciprocity agreement is a helpful arrangement for residents who cross state lines to work. It simplifies taxes and reduces the burden of having to pay income taxes to both states. As a resident of either state, if you work across the border, make sure to take advantage of this agreement and file your non-resident tax return accordingly.