That's slightly misleading. Universal Credit is not concerned with how many hours you work but in what you earn for your work.
There are two thresholds. One is called the conditionality threshold and set out by regulation; Regulation 90 of the Universal Credit Regulations 2013. For a single person that is set at 35 * the National Living Wage; earn that and you are not required to do anything else. Earn less and you may be required to look for more work/Pay and incentivised to do so by a punitive work search regime.
As this threshold tracks the national living wage it automatically increases year by year.
In practice there is a second, lower, limit called the Administrative Earnings Threshold. If you earn more than that although notionally expected to seek to increase earnings you'll be on a light touch regime to keep in contact with the Job Centre and not unduly hassled. This limit is set Administratively and was, for some years, £355/month for a single claimant and £494 for a couple.
At the end of this month it increases to £567 for a single claimant and £782 for a couple.
The Chancellor has proposed a further increase from January.
