E.g. A husband and wife partnership, makes a loss and fails to return their partnership return, before the deadline; Any penalty will impact on the whole family, but a double penalty will hurt even more.
Late Partnership Tax Returns incur a penalty of £100 per partner. this should be a single penalty, regardless of the number of partners, especially if the partnership has made little, or no profit (or even a loss).
If there must be a penalty, this should be a fixed penalty for the nominated responsible person. The other partner(s), should not be penalised individually.