My wife and I are looking at having her wedding dress from 6 years ago shipped from the US to us in Switzerland. When we moved here we left it in storage in the US since it was more convenient. If we had brought it with us, of course it would have been exempt from import fees because we already owned it at the time. Does anyone know if it is still the case, or would we have to pay fees based on its value the same as if we were buying it from abroad?

You should not be required to pay VAT on that, but the tricky part is the fact that it is being shipped - since you can't just make your case in front of a border agent as you would do with the dress in your luggage.

You'll need to make sure that the paperwork for the shipment is all correct and mentions that this shipment is VAT-free since it is your personal item. I am not sure about this one, but I think that if the customs decide to open and check - you'll still have to pay

As an anecdote - last month I forgot a personal item abroad and got it shipped via DHL. The sender declared everything correctly, but soon after DHL started spamming me saying that I owe them 50chf for VAT+customs fees. I told them that the sender sent me a scan of their shipment confirmation where it says black of white that the shipment should be VAT-free, and DHL's response was basically "well nevermind then".

All this happened a many years ago, but nonetheless:

When we first moved here, over 20 years ago, we left things in storage in the US.
Five years later we decided to ditch the storage and ship some of those things (furniture and a few oddments and whimsies) to Switzerland.

We were told by the shipping company that the exemption from duties and tax only applied to our first shipment, the second shipment was subject to tax and duties where applicable.

Of course, nothing in the second shipment was new, so we declared the estimated used-goods value.

The shipping company had some kind of formula to determine that, it was far less than the price of the goods new. Used goods - even a wedding dress - have almost no real value. (Fortunately sentimental value is not taxable )

All in all the tax and/or duty (I can never remember which is applicable) ended up being a very small amount.

As above, this was many years ago so do check on current regs.

Wedding dresses, if in good condition, certainly have or can have a significant second-hand value.

When you first declared your personal affects you should have declared other things that you would/could have been bringing later on. If you didn't do that then it doesn't necessarily prevent you from bringing the stuff in tax-free but it makes the burden on you higher.
You should probably include the personal effects form 18.44 with any shipment. Whether that will actually work or not I do not know.

When I was moving here from the US in 2009, I shipped many boxes to myself (including a lot of clothes) and was told that as long as I kept the value of the items in each box under 100 CHF (or maybe it was 100 USD -- I can't remember), marked the box as a "gift" on the form AND wrote "used -- personal belongings" on the form, then I wouldn't have to pay anything in customs or VAT. So that's exactly what I ended up doing, sending everything via the US post office, as that was the cheapest shipping method, and I didn't end up having to pay anything in terms of customs or VAT when it arrived here.

I don't think you even need to specify that it's a wedding dress on the customs form(s). You could just simply write "dress" -- and again, be sure to keep the value of it under a certain amount, on the form. I think it the max value was 100 CHF or USD back then, but it may have changed since then.

The limit now is 65CHF.

One issue is that if the courier loses your parcel, they will only refund the declared value I believe...

Thanks... that's good to know -- that it's 65 CHF now. Also, that's a good point about potentially needing to be refunded the declared value.

100chf if it’s a gift.

If items bear less VAT (I.e. books) then it's more. It's essentially not a limit of import but on how much VAT is free, passed that amount and you pay VAT on the whole plus any admin fee.

No, it's still 100CHF for personal gifts, as someone already mentioned.