To-infinitive after "should"

Question

I have this question: Should we use the to-infinitive after should in this case?

• Should he (to) take his offer seriously, we will have to reconsider our proposal.

When should we and should not use 'to-infinitive' after should in such constructions?

Answer 1

The general rule is with the auxiliary words "should/would/could/can/must" you need to use the so called "bare infinitive", without the word "to".

Should he take his offer seriously, ...

However with other auxiliary words the situation might be different:

Were he to take his offer seriously, ...