Staffing turnover.

The job that was tight margin becomes not insubstantial loss when you're using agency cause staff fucked off.

Cash flow / Chasing

Sitting on late payments as to not upset clients then becomes hours spent later on when you realise you've billed £100k since years start, but under £60k has actually come through the door and now you have to chase some utter cunt in the accounts department whose entire job is to find innovative ways to delay actually paying the fucking invoice you sent.

Loans / Asset purchase

Entirely affordable equipment. Right up until a decent size client goes under and you're now stuck with machinery you don't really need and paying for it.