Claimants of Working Tax Credits will soon need to inform Her Majesty's Revenue and Customs ( HMRC ) of any changes to their working hours.
Workers who claim tax credits have, during the pandemic, not needed to tell HMRC about the number of hours they have been working - but this this is set to change on November 25.
Any one who fails to make the change in time could be subject to a £300 fine.
People whose shifts haven't changed will not need to get in touch with HMRC.
For those that have, the government may need to reassess your allowance; depending on the assessment, the amount you receive could go up or down.

HMRC's director general for customer services, Myrtle Lloyd said in the past: "We introduced this measure last year to help support working families.
"It is vital that Working Tax Credit claimants who have benefited from it update HMRC with their working hours if they have reduced, and they won’t return to their normal level before November 25."
Changes to Working Tax Credit for 2021
Prior to the outbreak of coronavirus, any changes to working hours would need to be logged when claiming tax credits.
However during the pandemic HMRC said this information didn't need to be supplied, with any drops in working hours being treated as if workers were still working their normal hours due to the fluctuating hours of employees amidst furlough and hours cuts.
This meant that benefit payments were not affected by losses to work.
Changes after the 25th could mean that you allowance could once again go up, if your shifts do.
Anyone who has lost their job, had their hour changed permanently or been made redundant will also need to inform HMRC of the change.

Recipients of too much Working Tax Credit may have to pay the money back later.
Anyone who is charged the £300 fine for failing to inform HMRC of their change in circumstance could see the amount they owe by £60 per day until the balance their account.
Who is eligible for Working Tax Credit?
Working Tax Credit is available to UK workers on low incomes.
You can only claim Working Tax Credit if you already claim Child Tax Credit, and dependent on your age must work a certain amount in order to receive the allowance.
The hour per week requirements according to the government website are as follows:
- People aged 25 to 59 must work at least 30 hours
- People aged 60 or over must work at least 16 hours
- Disabled people must work at least 16 hours
- Single parents with 1 or more children must work at least 16 hours
- Couple with 1 or more children must work at least 24 hours between you (with one of the parents working at least 16 hours per week.
Workers can be employed, self-employed or a mixture of the two to qualify for credit and there is no upper limit to the amount you can earn due to the varying nature of peoples' situations.
Working Tax Credit is received by nearly two million Brits.
The maximum you can get is £3,240, however this isn't a flat rate, with the amount people received being means tested and dependent on their circumstances.
Anyone who isn't eligible to apply for Working Tax Credit can apply for Universal Credit instead.
If you and your partner are over the state pension age, you may also be able to apply for Pension Credit.