In the UK, HMRC (gov agency that is responsible for collecting tax) has a concept of Payment on Account [1]. You make 2 payments each year (Jan and Jul). The pa

In the UK, HMRC (gov agency that is responsible for collecting tax) has a concept of Payment on Account [1]. You make 2 payments each year (Jan and Jul). The payments are based on last years actual tax liability, so the assumption is you're earning broadly the same as the year pervious. The 2 payments made are then subtracted from your actual liability for the year once calculated. Perhaps implementing something like the above, just for yourself, would keep you broadly on track to cover your annual tax liability? [1] https://www.gov.uk/understand-self-assessment-bill/payments-on-account https://www.gov.uk/understand-self-assessment-bill/payments-...