The idea behind the registered letter is to make it 'official'. In the letter you can refer to the previous correspondence and point out that the caregiver agreed to provide the receipt. By registering the request the caregiver has to sign that she received the document. Thus providing you with the supporting documentation if you need to proceed further.

In Ontario, as a parent you can claim what you paid your daycare provider without a SIN #. But if Revenue Canada asks for a receipt they can disallow your claim. I am sure there are loop holes for everything, with documenation stating that the caregiver has still not provided the receipt will work in your favour.

I don't know what avenues are available to you as a parent to get a provider to supply you with either a receipt with her SIN or just her SIN or BIN (which btw you don't have to have a providers SIN, I NEVER EVER give mine out, instead I supply my BIN). Revenue Canada might be able to assist because they do have the authority to charge a provider who does not give out her SIN or BIN number.

Without harrrassing your old caregiver, have you tried writing the receipt yourself, leaving a blank space for the caregiver's signiture and SIN and request her to sign it in person (provide a duplicate for her records)? You may be completely right in that your old provider isn't providing the receipt on purpose because there wasn't a good relationship, but sometimes life does get busy, and we forget. I had a family that left daycare in the summer and I didn't even realize until January that I never provided them their annual receipt.

Another tidbit, I am sure you have already tried, but be ultrasweet when dealing with your old provider, as you catch more flies with honey than vinegar. Maybe start by saying, you are sure that the original receipt was lost in the mail so you are hoping that she will provide you with a duplicate receipt, or maybe ask if it has been prepared yet so that you can pick it up friday on your way home from work? Being sweet and not giving her an option to say no might work?

Oh if you have an accountant do you taxes you can have the accountant call your daycare provider for the SIN #, I had a daycare parent or two do that to me because I don't give my SIN # out and parents didn't realize they had my BIN # on the receipt.