Assalamu Alaikum Wa Rahmatullah Wa Barakatuhu,
Al-Hawl is not a year, it is different to a year, it is ten months and a half, and this is the Hawl for Allah’s (swt) saying: )وَحَمْلُهُ وَفِصَالُهُ ثَلَاثُونَ شَهْرًا(“…and his gestation and weaning [period] is thirty months” [Al-Ahqaf: 15]
If we subtract nine months of pregnancy, then we will be left with 21 months, i.e. every Hawl is ten months and a half, this is also for the saying of Allah (swt):)يُرْضِعْنَ أَوْلَادَهُنَّ حَوْلَيْنِ كَامِلَيْنِ(“Mothers may breastfeed their children two complete years” [Al-Baqara: 233].
That is 21 months after the delivery… Therefore Zakat is due every ten and a half months, which means every 7 years we give Zakat 8 times.