Maternity Certificate (Mat B1): Complete Guide
The Mat B1 (MATB1) is the certificate your midwife gives you to claim maternity pay. Here's what you need to know. It is a straightforward document, but understanding when you get it, what it is used for, and what to do if something goes wrong can save you a lot of stress later in your pregnancy.
What Is a Mat B1?
The Mat B1 is an official certificate — printed on NHS-headed paper and signed by your registered midwife or GP — that confirms your expected week of childbirth (EWC). It does not state your exact due date, but the week in which your baby is expected.Your employer or, if you are self-employed, the relevant benefits agency, uses the Mat B1 as evidence to process your entitlement to maternity-related payments. Without it, your employer cannot legally process Statutory Maternity Pay (SMP).
The form itself contains:
- Your full name and address
- Your expected week of childbirth
- The signature and name of your midwife or GP
- The date it was issued
It is a standard NHS form (form FW8 in some contexts, though MATB1 is the common name). Only a registered midwife or doctor can sign it.
When Do You Get Your Mat B1?
Your midwife can issue your Mat B1 from **20 weeks of pregnancy** onwards. In practice, most midwives hand it out at your **20-week anomaly scan appointment** or shortly after.You cannot get the Mat B1 earlier than 20 weeks — it is a legal requirement that it is not issued before this point. If you have your 20-week scan but your midwife does not mention the Mat B1, it is fine to ask for it at that appointment.
If you are under consultant-led care or have a more complex pregnancy, your consultant or a member of your GP surgery team may issue it instead.
When Do You Need to Give It to Your Employer?
You must give your Mat B1 to your employer **at least 15 weeks before your expected week of childbirth**. This deadline is set in law and relates to when you must give your employer notice of your maternity leave start date.To work out 15 weeks before your due date:
- Find the Sunday before your due date (or the due date itself if it falls on a Sunday) — this is the start of your expected week of childbirth
- Count back 15 weeks from that Sunday
If you miss this deadline, you may still be entitled to SMP but your employer may need to delay processing it. Always speak to your employer's HR department or payroll team if you are concerned about timing.
What Happens If You Lose Your Mat B1?
If you lose your Mat B1, ask your midwife or GP surgery to issue a replacement. There is no limit on how many can be issued, though in practice midwives may ask you to confirm you have genuinely lost it. It is sensible to make a photocopy of your Mat B1 as soon as you receive it and keep both copies in different places.Your employer should not need to keep the original permanently — once they have processed it, ask if you can have it back, as you may need it if you change jobs or for your own records.
Mat B1 and Statutory Maternity Pay
The Mat B1 is required for your employer to pay you **Statutory Maternity Pay (SMP)**. To be eligible for SMP you must:- Have been employed by the same employer for at least 26 weeks ending with the 15th week before your expected week of childbirth (the "qualifying week")
- Earn at least the Lower Earnings Limit (a weekly threshold set by the government each tax year) on average over the 8 weeks before the qualifying week
- Give your employer the correct notice
If you do not qualify for SMP — for example because you are self-employed, have not worked for your employer long enough, or earn below the threshold — you may instead be able to claim Maternity Allowance through the Department for Work and Pensions (DWP). Maternity Allowance has its own eligibility criteria and you claim it directly from the DWP rather than through your employer; you will still need your Mat B1 as evidence.
Mat B1 If You Are Self-Employed or on a Zero-Hours Contract
If you are self-employed, you will not receive SMP but may be eligible for Maternity Allowance. You will need your Mat B1 to support your claim to the DWP. Download and complete form MA1 from GOV.UK and submit it along with your Mat B1.If you are on a zero-hours or casual contract, your eligibility for SMP depends on whether you are legally classed as an employee and whether you meet the earnings and length-of-service criteria. If you are unsure of your status, Citizens Advice can help you understand your rights.
Frequently Asked Questions
### When do I get my Mat B1?Your midwife can issue your Mat B1 from 20 weeks of pregnancy — it cannot be issued before this point. Most women receive it at or shortly after their 20-week anomaly scan. If it is not mentioned at that appointment, ask your midwife directly. You need to give it to your employer at least 15 weeks before your expected week of childbirth, so do not leave it too long once you have it.
What if my employer loses my Mat B1?
Ask your midwife or GP to issue a replacement — they can do this, though you may need to confirm the original has been lost. It is worth making a photocopy when you first receive your Mat B1 to avoid this situation. If your employer loses it after processing your SMP, ask whether they kept a copy on file; if not, a replacement from your midwife should resolve the issue.
Can I claim Maternity Allowance without a Mat B1?
You need a Mat B1 (or a letter from your midwife or doctor confirming your expected week of childbirth) to claim Maternity Allowance from the DWP. The form MA1 on GOV.UK lists exactly what evidence you need to include with your claim. If you cannot yet get your Mat B1 because you are under 20 weeks, you can submit your claim early and send the Mat B1 once you have it.
Always speak to your midwife or GP for advice tailored to your individual pregnancy.
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