URGENT - Employer's letter needed for FLR(M)?

[Venezia]

Hi - this is my first post here.

We have an appointment on Wednesday for my husband's FLR(M) application. He currently holds a Tier 2 visa but wishes to change job. We satisfy the financial requirements through his salary alone (although mine would satisfy it too, but it slightly more complicated as I've just returned from maternity leave). We have both read the form and the guidance carefully but are confused by what we read online (including here).

Does he need an employer's letter, confirming his employment and salary, length of employment, the period over which he's been earning the salary required in the application, etc? I can't see this stated anywhere in the form or guidance but I've seen it mentioned in a number of posts here? We have very little time to obtain such a letter if it is required!

Thank you so mmuch for your advice.