Present Subjunctive: Regular 'IR' Verbs
Spanish: Cambridge International GCSE, topic 10.6.3
IR Verbs in the Present Subjunctive
To form the present subjunctive with IR verbs, take the present tense endings of AR verbs instead of the IR present endings. The first person singular will be the same as the third person singular. Here is the example for 'subir':

Suba - I go up

Subas - you go up

Suba - he/she goes up / you go up (formal)

Subamos - we go up

Subáis - you go up (plural)

Suban - they go up / you go up (formal plural)
Test yourself on Present Subjunctive: Regular 'IR' Verbs
'Vivir' is a regular IR verb. How do you say 'we live' in the present subjunctive in Spanish?
How do you say 'they go up' in the present subjunctive in Spanish?