More than 3.29 million families who currently claim tax credits have just two weeks to check their renewal packs, or risk missing out on thousands of pounds.
Working tax credits and child tax credits, which are both means-tested benefits, can provide extra money for disabled workers, those on low incomes and those responsible for children.
But you may be required to renew your application to prevent your payments being stopped.
Here, we explain who is eligible for tax credits and what you need to do.
HM Revenue and Customs (HMRC) sends out renewal packs to people who claim tax credits between April and July each year.
If your renewal pack says 'check now', you'll need to check if the details in the pack are correct. There's no need to do anything else if the details are up to date, as your tax credits will be renewed automatically.
On some packs, however, there's a red line across the front page that says 'reply now'. In this case, your tax credits must be renewed by the 31 July 2019 deadline, which is exactly two weeks from today.
If you don't have accurate figures for how much you earn, you can use estimated ones - just make sure you still submit by 31 July 2019. You'll then have until 31 January 2020 to provide the accurate information.
The tax credit office will let you know how much you're eligible to receive within eight weeks of receiving your renewal.
If you have questions, you can now ask Amazon's Alexa to 'open HMRC', and ask for help and information. Keep in mind that Alexa does not store any personal information, and you can't renew your tax credits using Alexa.
If you miss the 31 July deadline, your tax credits payments will stop.
HMRC may also recover any payments made to you between April and September of this year, meaning you could owe a hefty bill.
If you can show a 'good cause' for having missed the deadline, you may be given until 31 January to complete your renewal. But it's at HMRC's discretion to accept or reject the reasons you give.
To make sure you don't miss out, it's best to submit now. And if there's any possibility you'll miss the deadline, get in touch with HMRC as soon as you can.
In most cases, it's a legal requirement for you to keep HMRC updated with any changes to your income or family circumstances.
For example, you must let HMRC know within a month if:
Failing to let HMRC know about these changes could result in a £300 fine. You could also be fined up to £3,000 if you submit incorrect information, and HMRC can make you pay back any tax credits you may have been overpaid.
As of December 2018, there were more than 3.29 million families, caring for 6.04 million children, receiving tax credits.
To qualify for working tax credits or child tax credits, you'll need to meet the following criteria.
are for those aged 25 years or over and earn below a certain income level. Alternatively, people aged between 16 and 24 years can claim if they either have a child or a qualifying disability, as can those aged 60 or over who claim certain other benefits.
To be eligible, you must work a certain number of hours a week - over 16 for those under 25, and over 30 hours for those over 25.
You must also get paid for the work, or expect to be paid, and have an income below a certain level. While you can't usually claim working tax credits if you don't work, there are some exceptions, such as for those claiming statutory sick pay or statutory maternity pay.
To receive child tax credits, you must be responsible for at least one child who is either aged 16 or under, or is under 20 and enrolled in an eligible training or education course. You do not need to be working to claim child tax credits.
is a new government benefits system that replaces six existing payments with one overall scheme. It is gradually being rolled out across the UK and applies to those who are out of work or on low income.
If you are on the Universal Credit scheme, you can't apply for working tax credits or child tax credits, as your Universal Credit payments should replace these.