Single adult child - how to pay for the room?

[serita]

We are going on holiday as a family. It’s me and dh, Dd and her dh, and ds.

DS is single so will need a hotel room to himself. But it doesn’t really seem fair that he has to pay £150 a night when everyone else will be paying £75

You could divide what you, your husband and your son pay into 3, and he pays that?

No the single tax isn't fair.

Ideally split by five or if your DD and her DH don't want to, split by three as pp suggests.

I wouldn't saddle your dd with a share but I'd pay more to bring ds down to 75

Your dd and her dh are not obligated to contribute towards ds hotel room, but you and your dh could do so if you wished.

If it was a self catering house, I'd say split it 5 ways. But as everyone could just book their own rooms directly with the hotel, then the room charge is paid for by whoever is staying in that room. Why don't you just book two rooms, for you dh and ds, and bill your son half of a rooms cost.