Can I file without an eSteuerauszug?

Yes. The electronic statement is a convenience, not a requirement. You can complete the Wertschriftenverzeichnis yourself, as everybody did before the standard existed — it just has to be right.

What value do I use for a share on 31 December?

The official tax value from the ESTV Kursliste (ICTax), not the price your broker shows. Some cantons enforce the official figure, and the two are frequently different.

What is the commonest mistake?

Missing the deemed income on accumulating funds. A fund that reinvests rather than paying out still generates taxable income, the Kursliste publishes it per unit, and it appears on no broker statement anywhere.

Filling a Wertschriftenverzeichnis with no bank statement

What the form actually wants

For every security you held, on 31 December of the tax year:

What it is — name and ideally the ISIN or valor number.
How many you held.
Its official tax value at 31 December.
The gross income it paid during the year.
Any tax withheld — Swiss Verrechnungssteuer, or foreign withholding tax.

Three things people get wrong

1. Using the broker's price instead of the official tax value

The figure that belongs on the form is the official year-end Steuerwert published by the federal tax administration in the Kursliste, reachable through ICTax. Your broker's closing price is a market price, and it is frequently not the same number. Some cantons enforce the official one.

2. Missing the deemed income on accumulating funds

This is the big one, and it is invisible. A fund that reinvests its dividends instead of paying them out still generates income that is taxable in your hands. The Kursliste publishes that deemed income per unit. It appears on no broker statement anywhere, because your broker never paid you anything — so if you copy your broker's figures you will under-declare without noticing.

3. Putting foreign tax in the wrong place

Swiss withholding tax and foreign withholding tax are reclaimed by different routes. Verrechnungssteuer comes back in full through the ordinary Wertschriftenverzeichnis. Foreign tax is a credit claimed on the DA-1 supplementary sheet, and only if the total exceeds CHF 100. Below that you declare the income net and file no DA-1 at all.

The DA-1, and whether yours is worth filing

Doing it by hand, sensibly

List every position you held at 31 December, with quantity and ISIN.
Look each one up in ICTax for the tax year and take the official value.
Note the deemed income for any accumulating fund.
List every dividend and interest payment with its gross amount and the tax withheld.
Split the income: Swiss-source into the ordinary list, foreign-source onto the DA-1 if it clears the floor.
Round once, after summing — never per row.

Or have it done from the export you already have

That is what this service is. Upload your broker's own export and it produces the statement, including the parts that are easy to miss. Reading the file and showing you the summary is free; you pay only for the documents.