Monaco is part of France for VAT purposes. Contrary to the legislation, Shopify treats Monaco as a separate country. Moreover if a French consumer enters Monaco postal code the country of delivery is automatically switched to Monaco.
To override Shopify's behaviour, stores that are deliver goods to Monaco should be configured according to the article.
EAS will report orders to Monaco as IOSS reports to the France.
Step 1: Monaco should be set up as one of your taxable regions.
Go to Settings 
→ Choose Markets → Press Add market button
In the opened window set the name of the marked and search for Monaco and select it, press Add market button
Step 2: In the settings, choose Taxes and Duties, search for Monaco, and choose Monaco in the Country/Region table
Overrides applied in your shop to France should be also applied to Monaco.
Step 3: In the opened window set Country Tax rate to 20%, add all overrides that are persits for the France bay pressing Add a tax override and press button Save
Unfortunately, this setting will not allow for the 150 EUR IOSS threshold for sales to Monaco and VAT will be calculated for sales below and over 150 EUR. If your store is set up not to collect VAT for orders over 150 EUR for your EU sales, you will need to refund buyers from Monaco for the collected VAT for orders over 150 EUR.
This will not have effect on EAS treating IOSS orders.
EAS will always consider orders to Monaco as orders made to France and if the order intrinsic value is over 150 EUR the order will not be considered as IOSS.