Our situation: I am a "self-employed" (the quotation marks become clear later!) translator and my husband is an employee. My husband wanted to take three months off as shared parental leave. Originally, I had no plans to apply for maternity allowance/statutory maternity pay as I had saved enough money to keep paying myself and was worried about the restrictions that would be placed on us. However, his HR team informed him that I would have to apply for maternity allowance/pay for him to be eligible to take parental leave. They recommended that we use gov.uk's maternity calculator to figure out what to do.
So far, so good. I thought that I could apply for maternity allowance and that was it! HOWEVER, it turns out the maternity calculator fails to factor in the various types of "self" employment. I am the sole director and employee of a limited company - I alone am responsible for the success and running of the business. While I am off work, no-one will be covering for me. Various articles online said that, in this case, I should still be eligible for maternity allowance....They were wrong! After a few phone calls to accountants, HMRC and the Department for Work and Pensions, I found out that, as the employee of a company run by myself, I am eligible for statutory maternity pay and NOT maternity allowance (entitling me to a whopping 60p more a week!). You can apply to the DWP to have this money paid back to you, so you are not out of pocket.
Although the fact that my situation makes me "employed" may be obvious to tax or accounting experts, we found no clear information online confirming this and explaining what I would be entitled to, so I hope someone somewhere benefits from this brief summary!