We intended to make ‘Umrah on the first night of Ramadan. Therefore, we traveled to Makkah on the 26th of the month of Sha’baan and assumed Ihraam (ritual consecration) at Qarn Al-Manaazil, our due Meeqaat (designated point for assuming Ihraam), then we maintained the state of Ihraam until the month of Ramadan started. Hence, are we liable to anything? Was our Ihraam valid or should we have assumed Ihraam at At-Tan‘eem?
All perfect praise be to Allah, the Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
If you assumed Ihraam at the Meeqaat determined by the Sharee‘ah and maintained Ihraam until you performed ‘Umrah, then what you did was correct and your ‘Umrah was valid. It would not have permissible for you to assume Ihraam at At-Tan‘eem because you were already in the state of Ihraam.
That ‘Umrah, however, took place outside of Ramadan because one of its pillars, namely the Ihraam, took place before the month of Ramadan started. Assuming Ihraam at At-Tan‘eem or Al-Ji‘irraanah is permissible for those who are already in the sanctuary and out of the state of Ihraam. If they want to make ‘Umrah, they need to go outside the sanctuary to assume Ihraam. Otherwise, they must slaughter a sacrificial animal because they did not combine the two states of being inside and outside the sanctuary during the Ihraam for the ‘Umrah. If you want to make the ‘Umrah within the month of Ramadan, then you must go outside the sanctuary - and At-Tan‘eem is considered outside the sanctuary - so as to assume Ihraam, and then perform ‘Umrah.
Allah Knows best.