Hello Nikol,
I have a Chanel Boutique piece with a tag similar to yours. Have done lots of research in order to date the item as close as possible. No one was seemingly able to give me a definite guide on how to date the Chanel Boutique clothes.
The tag of your skirt shows 'Collection 9'. There are a number of other Chanel items with tags that show the words 'Collection' and a number, such as 18, 26, etc.
Here are just my thoughts that may or may not be correct. As we know, Karl Lagerfeld has started with Chanel in 1983. My idea would be that the tags might reflect his collections in their subsequent numbers, like Collection 1, then the next would be Collection 2, and so on. It would then depend on how many RTW collections would he have issued in a year. Could be three or four collections, I guess. This logic would bring me to a guess that his ninth collection, Collection 9, might have been appeared in about 1985 or so.
How does that sound for dating the jacket?