What's your way of dealing with irritating last minute requests?

Now I'm doing more tax work, I come up regularly against clients who when presented with final accounts and tax return to sign, ask whether I can make some sort of allowance for XYZ, or did I know about some other expenses (previously not notified to me). They plaintively ask whether it's not too late.

I am deliberately not flooding myself out with tax clients at present whilst I decide how to avoid blowing a personal gasket.

How do you deal with this type of irritation? They all know perfectly well that you are going to treat the data as complete unless you find a glaring anomally when you are doing the accounts. What they don't either know or care about is the aggravation of making all those adjustments and preparing all those pdfs again.

I could present them with accounts for prior approval before getting going on the tax package. Is that the best way forward in future?

Please throw a bucket of cold water over me before I self-explode!